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t\fc >£{£,% Marketing Research Report No. 568 



Layouts and Operating Criteria for 
Automation of Dairy Plants Processing 

MILK and HALF-AND-HALF 









UNITED STATES DEPARTMENT OF AGRICULTURE 

Agricultural Marketing Service 
Transportation and Facilities Research Division 



Preface 

The study on which this report is based was conducted and the report prepared by Paul H. Tracy, 
of DeLand, Fla., under a contract with the U.S. Department of Agriculture. The purpose of the 
study was to provide dairy plant operators with data and guidelines that could be used in establishing 
and operating special-purpose milk plants (plants that handle and package only fluid milk and half- 
and-half) more efficiently. The report deals primarily with the use and benefits to be derived from 
automated equipment. The study is part, of a broad program of research aimed at improving market 
efficiency for farm products. 

This is the first of a group of six reports for which work is under contract. Subsequent reports 
will deal with improved layouts and operating criteria for multipurpose fluid milk plants (those 
handling milk, half-and-half, cream, chocolate drink, and buttermilk), plants manufacturing ice 
cream and ice cream novelties, plants manufacturing cottage cheese, cream cheese, and cultured milk 
and cream, cheddar cheese plants, and plants manufacturing sweet cream butter and dried nonfat milk. 

Pictures of equipment in this report were contributed by various manufacturers; use of the 
pictures does not constitute endorsement of the equipment by the U.S. Department of Agriculture. 
Competitive equipment is available which will perform the same functions. 



Contents 



Page 

Summary 4 

Introduction 5 

Plant handling 35,000 gallons of milk a week 6 

Assumptions with respect to plant operations 6 

Suggested layout of the plant 7 

Components of the facility 7 

Arrangement of plant components 15 

Provision for plant expansion 16 

Plant site 16 

Schedule of equipment use 17 

Receiving and processing 17 

Filling cartons 19 

How the plant operates 19 

Control panel operations 19 

Other operations 24 

Labor requirements 25 

Estimated equipment costs 26 

Possible benefits from labor-saving devices 26 

Plant handling 105,000 gallons of milk a week 26 

Assumptions with respect to plant operations. _ _ 26 



Page 

Suggested layout of the plant 26 

Components of the facility 26 

Provision for plant expansion 31 

Plant site 31 

Schedule of equipment use 31 

How the plant operates 35 

Labor requirements. 35 

Costs and possible benefits of labor-saving equip- 
ment 37 

Appendix: Refrigeration, heating, and ventilating 

systems 37 

Plant handling 35,000 gallons of milk weekly 37 

Refrigeration system 37 

Heating system 40 

Ventilation and air conditioning 41 

Plant handling 105,000 gallons of milk weekly___ 42 

Refrigeration system 42 

Heating system 43 

Ventilation and air conditioning 43 



Washington, D.C. 



Issued March 1963 



Summary 



Automated and highly mechanized operations 
can reduce costs for milk plants that specialize in 
processing raw milk into market milk and half- 
and-half. 

It is estimated that such a special-purpose milk 
plant handling 35,000 gallons of milk weekly can 
reduce its labor cost $26,000 annually by using 
automated and highly mechanized equipment and 
improving its layout. The production per man- 
hour in an automated plant is 125 gallons of milk, 
compared to 79.5 gallons for a nonautomated plant. 
The estimated cost of the equipment required to 
make these savings is $85,000 greater than the cost 
of the equipment required for a nonautomated 
plant. If 20 percent of the cost of the equipment is 
allowed annually for depreciation, maintenance, 
taxes, and interest on investment, the savings 
should amortize the additional cost of equipment 
in about 9l/ 2 years. 

The same kind of plant handling 105,000 gallons 
of milk weekly can reduce its labor cost $39,000 
annually and increase its production from 154.3 
to 239 gallons per man-hour. The estimated cost 
of the equipment required to realize this saving 
is $110,000 greater than the equipment cost for a 
nonautomated plant. If 20 percent annually is 



allowed for depreciation, maintenance, taxes, and 
interest on investment, the savings should amortize 
the additional cost of equipment in about 6^ 
years. 

Automated operations that make part of this 
reduction in cost possible are in the receiving of 
raw milk, the separating, standardizing, pasteuriz- 
ing, and homogenizing processes, and the cleaning 
of equipment associated with most of these opera- 
tions. The use of highly mechanized equipment 
for filling cartons, putting cartons in cases, stack- 
ing cases, and handling empty cases also accounts 
for part of the reduction in costs. 

Layouts are suggested for special-purpose milk 
plants processing 35,000 gallons and 105,000 gal- 
lons of market milk and half-and-half a week. 
The layouts show the possible arrangement of 
equipment and the flow of products, containers, 
and supplies through the plants. The layout of 
each plant provides for future expansion adequate 
to handle twice the volume. For the plant han- 
dling 35,000 gallons of milk a week, a 100-percent 
increase in plant volume requires a 37-percent in- 
crease in plant area. For the plant handling 
105,000 gallons a week, a 100-percent increase in 
volume requires a 41 -percent increase in plant area. 



Layouts and Operating Criteria for 

Automation of Dairy Plants Processing 

MILK and HALF-AND-HALF 



By P. H. Tracy 



Introduction 



Interest in mechanization in the dairy industry 
has been growing since the turn of the century. 
It was soon realized that mechanical refrigeration, 
power- driven machines, and mechanically oper- 
ated bottle fillers and cappers were necessary for 
a rapidly growing and competitive industry if 
operating costs were to be held in line. 

Today, the dairy industry is even more com- 
petitive, and management is looking to automa- 
tion to lower costs. Automation is a phase in the 
evolution of mechanization — a stage in which me- 
chanical operations are brought under automatic 
controls. It may include the remote control of 
machinery or the programing of a series of op- 
erations to occur in sequence. Its purpose is a 
reduction in manpower requirements without a 
sacrifice of either healthfulness or quality of the 
finished product. 

In 1958 and 1959, a preliminary survey was 
made of 75 dairy plants in 30 different States 
to determine the extent to which automation had 
been applied in dairy plants and the effects of 
automation on operating costs. The results of 
the survey showed that automation of operation 
was limited and that in some plants better mech- 
anization of operations would be necessary before 
complete automation could be achieved. 

The survey also showed that production costs 
varied widely among plants and that faulty 
plant layouts, obsolete methods and facilities, and 
poor locations were contributing to excessively 
high production costs. 

Dairy plant operators throughout the country 
have manifested an interest in plant automation, 
but many lack specific information about how 
automation can be applied in a practical manner. 

One of the major factors limiting the efficiency 
and use of automated methods in dairy plants 
has been the wide diversification of operations. 
Many plants process several different grades of 
milk, cream, flavored drinks, cultured milk prod- 
ucts, fruit drinks, and soft cheeses, using differ- 
ent styles and sizes of packages. Such diversifl- 



1 Formerly professor of dairy technology, Department 
of Food Technology, University of Illinois. 



cations, unless volume is sufficient, lead to prob- 
lems in production and management and higher 
processing costs. Consequently, there is some 
trend toward the establishment of special-purpose 
plants, which process only a few items. A 
special-purpose plant, for the purposes of this re- 
port, is one that handles and packages only fluid 
milk and half-and-half. 

The purpose of this study, therefore, is to pro- 
vide information to operators of special -purpose 
milk plants that would assist them in improving 
their present operating methods and plant lay- 
outs and in using automated methods either in 
new plants or in remodeled plants. 

The types of equipment essential for automated 
and mechanized methods of operation are listed, 
and plant layouts are given showing arrangement 
of the equipment to provide the most efficient op- 
eration. Plans for the layout on the plot are 
also given. 

Two plants of different sizes illustrate the prin- 
ciples of operating criteria. One plant would 
handle 35,000 gallons of milk a week and the 
other 105,000 gallons. Plans for the plants are 
intended to illustrate only the principles of layout, 
design, and size in relation to volume and products 
handled. These plans are not suggested for any 
specific market or location. 

Dairy plant operators planning the construc- 
tion of new plants or the expansion of existing 
plants should consult engineers, dairy technolo- 
gists, and local health department officials for 
assistance in the preparation of actual plant 
designs. 

Estimates are made of the savings that would 
result in operation of plants with the equipment 
and layouts given over typical, nonautomated 
plants. 

The following description is given to point out 
the differences between automated and nonauto- 
mated plants, as used in this report. 

Major operations in special-purpose milk 
plants consist of receiving raw milk, processing 
the raw milk into pasteurized, homogenized milk 
and half-and-half, packaging these products in 
half -gallon, quart, or pint containers, packing the 



containers in cases, storing and loading out cases 
of products, receiving and storing empty cases, 
and cleaning equipment. 

Receiving and Processing Milk. — A nonauto- 
mated plant uses hand-operated equipment and 
valves to receive and process milk and to trans- 
fer it between pieces of equipment during stand- 
ardizing, pasteurizing, and homogenizing. In an 
automated plant, equipment used in receiving and 
processing is operated from a central control 
panel. Valves that direct the flow of milk be- 
tween pieces of equipment are automatically set 
when a pump or other piece of equipment is started 
at the control panel. 

In addition to remote-controlled valves and a 
central control panel, other differences are in the 
methods of standardizing milk prior to pasteuri- 
zation. A nonautomated plant uses a tank gage: 
when milk is added to the tank, a worker waits 
until the gage shows the desired amount, then 
manually cuts off the pump and valves. In an 
automated plant, tanks are equipped with highly 
accurate weight-sensing devices that are con- 
nected to the control panel. Weight readings are 
taken at the panel, and specified amounts of milk 
are automatically added by operating controls at 
the panel. 

Packing Cartons ix Cases and Haxdlixg 
Cases. — In a nonautomated plant, cartons of milk 
are hand-packed in cases. Empty cases are 
placed one by one on a conveyor that moves them 
through a washer and then to the area where cases 



are packed. Packed cases are moved one by one 
by conveyor to the cold room, where they are 
hand-stacked for storage or loading out. In an 
automated plant, cartons are packed in cases by 
machine. The handling of empty cases requires 
much less time so that the worker is free for other 
duties. The worker stacks cases five high on the 
conveyor where a supply is accumulated by use of 
a stack feed magazine. The cases are then me- 
chanically unstacked, moved through the washer, 
and then to the machines that pack cases. Packed 
cases are stacked five high on the conveyor by an- 
other machine for transport to the cold room. 

Cleaning Equipment. — The required cleaning 
and sanitizing of equipment used in processing 
milk has always been a time-consuming job. In 
nonautomated plants, equipment is constructed 
so it may readily be dismantled for cleaning and 
sanitizing. Use of cleaned-in-place (CIP) sys- 
tems that circulate the required rinses and clean- 
ing and sanitizing solutions through equipment 
has reduced the time spent in taking equipment 
apart and cleaning it, but some dismantling of 
equipment parts is still required. 

In an automated plant, as much of the equip- 
ment as possible is constructed to be cleaned in 
place by the CIP system, which is set up to work 
automatically from the control panel. The se- 
quences and timing of rinses and cleaning and 
sanitizing solutions are programed for the par- 
ticular piece of equipment being cleaned. 



Plant Handling 35,000 Gallons of Milk a Week 



In developing principles and criteria for use in 
planning new or remodeling old special-purpose 
milk plants with automated methods, the primary 
objectives were as follows : (1 ) To reduce the labor 
required for receiving, processing, packaging, 
storing, and loading out milk; (2) to maintain 
the quality of the finished product; (3) to main- 
tain uniformity of the product; (4) to reduce in- 
plant loss of milk; and (5) to remove some of the 
drudgery of plant work caused by poorly mech- 
anized methods. 



Assumptions With Respect to Plant 
Operations 

.Many factors affect the efficiency of milk plant 
operations. There are variations in the volume of 
milk handled from day to day, as well as seasonal 
and holiday variations. Plants receive milk 7 
days a week and in many instances have little con- 
trol over the time it arrives. Frequently, plants 
receive milk both in tank trucks and in cans. The 
percentage of butterfat and solids-not-fat varies. 
In many plants milk is packaged and loaded out 



6 or 7 days a week, and in most plants milk prod- 
ucts are packaged in different types and sizes of 
containers. In the handling of milk there is an 
in-plant loss averaging about 1 percent. Most 
plants carry an operating reserve of milk, result- 
ing at times in an excess of butterfat or skim milk, 
and most plants have to dispose of returns of un- 
sold packages of milk. 

For a plant handling 35,000 gallons of milk a 
week it is assumed in this report that(l) the 
plant will purchase 80 percent of its milk from 
local producers and the remaining 20 percent from 
marketing associations; (2) all milk will be re- 
ceived in tank trucks; (3) milk received will av- 
erage 3.8 percent butterfat and 8.9 percent solids 
not fat; (4) milk will be processed into homoge- 
nized, pasteurized milk with a butterfat content 
of 3.5 percent and into half-and-half with a butter- 
fat content of 11 percent; (5) there will be no in- 
plant loss; (6) approximately TO percent of the 
total volume of milk pasteurized will be packaged 
in half -gallon containers, 30 percent in quart con- 
tainers, and the half-and-half in pint containers: 
(7) all products will be packaged in plastic- 
coated paper containers; (8) a 16-quart universal 



case will be used for all packaged products; (9) 
the drivers of retail route trucks will load their 
own trucks, and the plant personnel will load the 
wholesale trucks; (10) byproducts for route sales 
will be purchased from outside processors, and 
these items will be received daily at a time best 
suited to plant operations; (11) byproduct sales 
will be 20 percent of the total daily sales ; and (12) 
milk and half-and-half will be stored in the cold 
room overnight. 

The assumed inventory and processing schedule 
is shown in table 1. The plant will receive raw 
milk 7 days a week, process milk 5 days, and dis- 
tribute milk 6 days. Since the distribution is 
almost evenly divided over 6 days, the plant is 
designed to provide 5,830 gallons per day of 
finished product Monday through Friday, and 
5,850 gallons on Saturday. 

Since the plant does not process milk on Sun- 
day and Wednesday, it should produce enough 
product on Monday and Tuesday, plus the carry- 
over, to handle 3 days' sales. The production 
needed each of these 2 days is 7,500 gallons — 7,200 
gallons of market milk and 300 gallons of half- 
and-half. 

Since the plant operates during daytime hours, 
sufficient packaged products must be on hand 
Tuesday evening for loading retail and wholesale 
trucks on Wednesday and Thursday mornings. 
Requirements for these 2 days total 11,660 gallons. 
Thus, the plant should be designed to store this 
amount of finished products plus the byproducts 
purchased from outside sources. On Thursday 
morning, after trucks have been loaded and before 
processing starts, the finished product inventory 
is zero. 



The raw-milk inventory is controlled by the 
amount of milk purchased from a milk marketing 
association. Since processing does not occur on 
Wednesday or Sunday, deliveries from the milk 
marketing association 'are adjusted so that all raw- 
milk storage tanks are empty on Tuesday and 
Saturday evenings when processing is completed. 



Suggested Layout of the Plant 

The suggested layout of the plant is shown in 
figure 1. The layout is arranged to give consider- 
ation to product and container flow, space utiliza- 
tion, equipment arrangement, and future 
expansion. 

• The suggested plant is irregular in shape. 
Roughly, its depth is 160 feet, and its width at the 
widest point is 126 feet. It provides approxi- 
mately 11,573 square feet of usable floor space. 



Components of the Facility 

The following are the major components of the 
proposed plant: (A) Tanker-receiving shelter; 
(B) processing and filling room; (C) cold room; 
(D.) dock for loading retail and wholesale trucks 
and receiving empty cases; (E) storage room for 
empty cases; (F) storage room for paper con- 
tainers; (G) dry storage room for miscellaneous 
supplies; (H) laboratory and plant office ; (I) re- 
frigeration equipment room; (J) boiler room; 
(K) room for CTP equipment; (L) toilet and 
locker room for plant workers; and (M) general 



Table 1. — An assumed inventory and processing schedule for a plant handling 35,000 gallons of 

milk a week 



Milk inventory 


Day of week 




Mon. 


Tues. 


Wed. 


Thurs. 


Fri. 


Sat. 


Sun. 


Beginning raw milk inventory 


Gal. 

4,000 

4,000 


Gal, 

500 
7,000 


Gal. 


4,000 


Gal. 

4,000 

4,000 


Gal. 
1, 330 
6, 670 


Gal. 
1, 330 
5,330 


Gal. 



Raw milk receipts 1 


4,000 






Total 


8,000 


7, 500 


4,000 


8,000 


8,000 


6, 660 


4,000 






Processed milk: 2 
Market milk___ 


7, 200 
300 


7, 200 
300 






6, 400 
270 


6,400 
270 


6,400 
260 





Half-and-half 









Total 


7,500 


7, 500 





6, 670 


6, 670 


6,660 









Raw milk holdover 


500 
5, 830 
9, 990 




5, 830 

3 11, 660 


4,000 
5, 830 
5, 830 


1, 330 

5, 830 

6, 670 


1,330 

5, 830 
7, 510 




5, 850 
8, 320 


4,000 


Finished products sales 





Finished products holdover 


8, 320 








* Mllk received from milk marketing association bv davs: Tuesday, 3,000 gallons; Friday, 2,670 gallons; Saturday, 
M30 gallons. The rest of the milk is received from local producers. 

2 Figures rounded to the nearest ten. 

3 The amount of finished products needed for Wednesday and Thursday distribution. 



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office area. Figure 1 shows the arrangement of 
each item of equipment in each component, Eacli 
item of equipment is numbered and is referred to - 
by number (in parentheses) in the discussion of 
the various components. 

The components are arranged in the layout to 
provide for short, direct paths of flow for products 
and containers to minimize plant congestion, 
amount of piping and wiring needed, and plant 
labor requirements. Space requirements for the 
various components are based on the equipment 
needed plus an allowance for working space. Sizes 
of storage rooms are determined by the number 
and size of items to be stored and the methods of 
stacking. Allowances are made in all rooms for 
aisles, according to the types of traffic handled. 
The equipment within the various components is 
arranged for economy of movement of products 
and containers and for the most efficient perform- 
ance of operations. The plant is arranged so that 
expansion will not present a major construction 
problem. 

Tanker-Receiving Shelter 

If we assume that the plant receives raw milk 
from local producers in 1,800-gallon pickup tank 
trucks and from milk marketing organizations in 
3,000-gallon semitrailer tank trucks, the peak num- 
ber of trucks arriving at the plant for unloading 
on any given day would be four. The amount of 
raw milk received and the source are shown by 
day of week on the inventory schedule (table 1). 
The truck tanks are cleaned after delivering milk. 

The tanker-receiving shelter and the dock pro- 
vide space for two trucks at a time, so that one 
may be cleaned while the other is delivering milk. 
Trucks back into the shelter, which is 26% feet 
wide and 411/4 feet long. The receiving clock is 
6 feet wide. A platform, 3 feet wide by 28y 2 feet 
long, running lengthwise down the shelter from 
the center of the receiving clock, divides the shelter 
into two truck positions. Platform height should 
be even with the walkway on tank trucks to make it 
easy for workers to get to the tank manhole. 

Receiving pump (2), which removes milk from 
trucks at the rate of 180 g.p.m. (gallons per min- 
ute) is located on the dock. Other equipment, in 
the shelter is the CIP (cleaned-in-place) assembly 
(33) for washing truck tanks and the CIP solution 
return pump (34). The CIP washer assembly is 
mounted on a hoist on a monorail to facilitate mov- 
ing it to and from the tank manholes and from one 
truck to the other. The solution return pump 
returns the washing and sanitizing solutions to the 
automatic CIP unit (31) for recirculating through 
other equipment being washed. A hose should be 
provided for connecting tank trucks with built-in 
spray balls directly to the CIP unit. Spray balls 
distribute the cleaning solutions, and the tank 
washer assembly is not needed to wash these 
trucks. 



The floor of the tanker-receiving shelter should 
be constructed of reinforced concrete pitched 
toward the rear at not less than y 2 inch per foot to 
permit complete and rapid draining of milk from 
the tank trucks. A floor drain is located near the 
edge of the receiving dock. Power-operated over- 
head doors allow the area to be closed off from dust 
and insects while tank trucks are being serviced. 

Processing and Filling Room 

The processing and filling room provides space 
for the control panel; processing equipment; 
equipment for filling cartons, packing them in 
cases, and stacking the cases; and equipment for 
cleaning dismantled machinery. Raw-milk stor- 
age tanks are located adjacent to the room and for 
the purpose of this report are considered a part of 
the processing equipment. 

The area housing the control panel, processing 
equipment, and filling, casing, and stacking equip- 
ment is 49 feet 6 inches by 40 feet. It contains 
1,980 square feet of space. The area housing the 
raw-milk storage tanks is 22 feet 9 inches by 41 
feet 6 inches. A part of this area is aisle space, 
used in the processing operations, and is con- 
sidered to be part of the processing and filling 
room. Therefore, the processing and filling room 
contains 2,300 square feet of space. 

The walls of this area should be constructed of 
ceramic tile, the ceiling of moisture-resistant ma- 
terial, and the floors of concrete or tile. The floor 
pitch should be 14-inch per foot to all drains to 
provide for proper drainage. A ceiling height of 
14 feet would provide space for overhead utilities 
and adequate ventilation. 

Control Panel.— The control panel is the center 
of operation of all the automated equipment in the 
plant. 

It contains selector switches and pushbuttons for 
the following operations: (A) Receiving raw 
milk; (B) transferring milk and milk products to 
and from various equipment ; (C) determining the 
weight of milk and milk products; (D) moving- 
milk through the HTST (high temperature, short 
time) pasteurization system, which includes ho- 
mogenization ; (E) directing processed milk to the 
filling machines; and (F) cleaning various equip- 
ment with the CIP system. 

The panel has individual controls for starting 
and stopping agitators and refrigeration in var- 
ious equipment, and for starting and stopping 
equipment used in pasteurization and homogeni- 
zation. 

There are various recorder-controllers (instru- 
ments which record and control temperature or 
pressure or other factors) for pasteurization, ho- 
mogenization, and CIP cleaning. A chart records 
raw-milk temperatures. An air-pressure gage in- 
dicates the air supply for remotely controlled 
valves, and a pushbutton controls electric power to 
instruments in the panel. 



A diagram of the suggested control panel is 
shown in figure 11, page 21. The panel is about 4 
feet 7 inches high and 9 feet long. The back of 
the panel should be easily accessible for service 
and maintenance work. 

Raw-Milk Storage Tanks.— Three 4,000- 
gallon raw-milk storage tanks (4, 5, 6) hold raw 
milk received from tank trucks. These tanks are 
also used to prepare standardized milk (milk ad- 
justed to a standard butterfat content) and to hold 
skim milk used in standardizing and standardized 
milk ready for pasteurization. A 600-gallon tank 
would be adequate for skim milk storage but 
would not provide the flexibility of use of a 4,000- 
gallon tank for any of the three functions. 

The tanks are located side by side with the front 
of the tanks extending through the processing 
room wall and the bulk in the refrigeration equip- 
ment room. This location eliminates the frequent 
cleaning of tank exteriors that would be required 
if they Avere in the processing room. 

The tanks are equipped with agitators, used in 
standardizing milk, and spray balls for use with 
the CIP system. 

Each tank has 60 square feet of refrigerated sur- 
face on the bottom to provide a normal storage 
temperature of 40° F. The tanks should have 
thermocouples attached to the linings and wired 
to a multirecord instrument in the control panel, 
where the temperature of the product in each tank 
is recorded continuously on a strip chart. 

For automated weighing of tank contents, tanks 
should be mounted on four legs, two on each side, 
with load cells (weight -sensing equipment) at- 
tached to the legs on one side. The load cells are 
connected to the control panel where a direct read- 
ing in pounds of product is given. Electrical im- 
pulses from the load cells can also be used to start 
motors, sound alarms, and change valve settings 
when the tanks are nearly full or nearly empty. 
Several types of load-cell systems are available 
which will perforin these functions. Rubber col- 
lars should be installed around the tanks to pre- 
vent contact with the wall so there will be no 
interference with the load-cell system. All serv- 
ice connections to the tanks should be made of 
flexible materials. 

A three-line sanitary manifold system, sup- 
ported by pipes anchored to the floor, is located in 
front of the tanks (fig. 2). This system is used 
for all movement of products in and out of the 
raw-milk storage tanks. Air-operated valves in 
the system control the flow of milk. 

One line is used for receiving and standardiz- 
ing; the second to feed standardized milk to the 
HTST pasteurization system: and the third is 
used to return skim milk from the separator to 
the tanks or to transfer milk from one tank to 
another. A centrifugal pump (7) is used to trans- 
fer milk from one tank to another. 

Figure 3 shows an isometric drawing of the 
tanks with the manifold svstem and load cells. 



10 




Figure 2. — A three-line manifold system for filling, 
emptying, and cleaning raw-milk storage tanks. 



An aisle 8 feet wide should be provided in front 
of the tanks to allow space for the manifold as- 
sembly and a passageway. 

Processing Equipment. — The processing equip- 
ment consists of a variable-speed positive dis- 
placement pump (8), a separator-clarifier that 
separates 5,500 pounds of cold milk per hour or 
clarifies 12,000 pounds per hour (9), a balance 
tank (12), a vitamin feed cabinet (13), a plate 
heat exchanger with a capacity of 1,400 gallons 
per hour (g.p.h.) (14), a hot water heating and 
circulating unit (50), a positive displacement tim- 
ing pump (15), a holder tube (16), an ultra-high- 
temperature-heater (UHTH) system (17), a ho- 
mogenizer with a capacity of 1,400 g.p.h. (18), a 
400-gallon vat used for preparing half-and-half 
(10), a 1,000-gallon surge tank for pasteurized 
milk (19), and a 600-gallon surge tank for pas- 
teurized half-and-half (20) . The equipment is ar- 
ranged in the suggested layout for the most direct 
flow of products and with adequate space between 
major items for cleanup and passageway. Each 
item of equipment is discussed according to the 
function it performs. 

The positive displacement pump (8) pumps the 
raw milk from the storage tanks to the separator- 
clarifier (9). The separator-clarifier separates 
raw milk into skim milk and a product containing 
15-percent fat and clarifies milk (removes ex- 
traneous material and leucocytes). Actually, the 
separator-clarifier is a triprocess machine. It may 
be used as a separator, clarifier, or standardizer. 
For the proposed plant the machine would be used 
as a separator early in the day and as a clarifier 
later in the day; it would not be used for 
standardizing. 

The vitamin feed cabinet (13) provides the 
vitamin supply for the milk; it is portable and 
has a refrigerated compartment. 



LOAD CELLS - 2 EACH TANK 



5 | RECEIVE 8 STANDARDIZE 
M TO HTST 



SKIM S TRANSFER 




TO CONTROL PANEL 



AUTOMATIC VALVES 



Figure 3. — Raw-milk storage tanks are equipped with automatic valves to control the flow of milk and load cells for 

weighing tank contents. 



The following equipment is considered as part of 
the HTST system in this report: The clarifier, 
the balance tank, the plate heat exchanger, the 
holder tube, the ultra-high-temperature heater, 
and the homogenizer, 

The balance tank (12) assures a constant supply 
of milk in the system. It is equipped with high- 
and low-level probes that are wired to start or stop 
pumps or other equipment in the HTST system as 
the milk in the tank reaches certain levels. 

The plate heat exchanger (14) heats raw milk 
to destroy certain bacteria and also cools pasteur- 
ized milk. It consists of three major sections — 
a regenerative section, a heating section, and a 
cooling section. Cold raw milk and hot pasteur- 
ized milk flow between alternate plates in the 
regenerative section so that the cold raw milk cools 
the hot pasteurized milk and the hot pasteurized 
milk warms the raw cold milk. The same principle 
of heat exchange is used in the heating and cooling 
sections. Hot water from the water heating and 
circulating unit (50) flows between alternate plates 
in the heating section and further increases the 
temperature of the raw milk. Refrigerated water 



(34° F.) further cools the pasteurized milk in the 
cooling section. 

The positive displacement pump (15) sucks milk 
from the balance tank through the regenerative 
section and pushes it to the heating section. The 
holder tube (16) holds milk for 16 seconds to insure 
proper pasteurization. 

The ultra-high-temperature heater (17) insures 
uniformity of flavor by removal of certain feed 
and weed flavors, which may occur in milk, and 
improves the keeping quality by destroying bac- 
teria. The heater consists of an infuser and a vac- 
uum cylinder. The infuser injects culinary steam 
into milk and heats the milk. The infuser should 
be equipped with a moisture and condensate sep- 
arator at the steam inlet to separate liquid particles 
from the steam and keep them from entering the 
infuser. The vacuum cylinder cools the milk and 
removes slightly more water from the milk than 
was added to it by the steam injection. 

The homogenizer (18) breaks up the butterfat 
globules. 

The two pressurized surge tanks (19 and 20) 
receive milk and half-and-half from the HTST 



665977 O— 63- 



11 



system and maintain a balance in flow rate of milk 
or half-and-half between the HTST system and 
the fillers. An air pressure of about 5 pounds 
maintained in the tanks causes milk to flow from 
the tanks to the fillers. The tanks are equipped 
with agitators and with thermocouples that are 
connected to a temperature recording chart in the 
ratio recorder controller in the control panel (1). 
They are also equipped with remotely controlled 
air-operated valves, which permit milk and half- 
and-half to flow to the proper filler. 

Construction of the vat (10) used in preparing 
half-and-half provides for both cooling by sweet 
water and heating by steam. The vat is equipped 
with load cells, an agitator, and a thermocouple 
that is connected to the raw-milk temperature 
recorder in the control panel. The vat is pressur- 
ized and is also equipped with a remotely con- 
trolled, air-operated outlet valve. This valve 
permits half-and-half to flow to the HTST system. 

Filling, Casing, and Stacking Equipment. — 
Filling, casing, and stacking equipment consists of 
a filler for quart and pint cartons (21), a filler for 
half -gallon cartons (22) , an automatic case divider 
(29), two automatic casers (23), two automatic 
case stackers (24), and an above-floor conveyor 
(30). The quart-pint filler (21) fills 45 cartons 
per minute and the half-gallon filler fills 33 cartons 
per minute. The fillers are arranged so as to pro- 
vide easy access between the carton entry point on 
the filling machines and the paper-container stor- 
age room. Pallets loaded with containers may be 
placed adjacent to the operator's platform at the 
machines to facilitate loading the magazine on the 
fillers. 

The automatic case divider (29) permits cases to 
flow to both automatic casers as required (fig. 4). 
Carton conveyors with each filler transport cartons 
of milk from the fillers to the automatic casers. 

The two automatic casers (23) are arranged 




alongside the fillers so they can be easily observed 
from the operator's platform. One packs 9 half- 
gallons per case ; the other packs 16 quarts or 28 
pints in a case (pints are packed in two tiers). 

Two automatic case stackers (24) stack cases 
five high (fig. 5). The stackers have a capacity 
of 15 cases per minute. 




FlGUEE 5.- 



-The cases of milk are being discharged from 
automatic case stackers. 



Figure 4. — An automatic case divider with cover removed. 
The divider directs the flow of cases to the two auto- 
matic casers as they are needed. 



Above-floor conveyor (30) transports empty 
cases to the fillers; then it transports filled cases 
to the stackers, and finally to the cold room. The 
above-floor conveyor is part of a conveyor system 
that runs from the processing and filling room 
through the cold room, along the dock outside 
the cold room, through the empty-case storage 
room, and back into the processing and filling 
room. Most of the system is at floor-level and is 
identified as in-floor conveyor (25). 

Eqttp3ient for Cleaning Dismantled Ma- 
chinery. — A portable recirculating unit (35.) is 
suggested for the processing and filling room for 
cleaning equipment that must be partially dis- 
mantled. This "clean-out -of -place'' (COP) unit 
consists of a tank, pump, and motor. The pump 
circulates cleaning solution over equipment parts 
placed in the tank. 

Cold Room 

The cold room should be designed for receiving, 
storing, and loading out milk and milk products 
efficiently. The space requirements for the room 
should be determined by the volume and type of 
products to be stored, the sizes of the containers in 
which the products are . packaged, the sizes and 
number of cases needed, the method used in 
storing milk, the method of stacking cases, the 
length of the storage period, and the amount of 
conveyor and aisle space needed to provide for a 
free flow of products into and out of the room. 



12 



As previously stated, the maximum holdover 
for milk processed in the plant would be 11,660 
gallons. The holdover of byproducts purchased 
from outside sources is estimated at 20 percent of 
one day's sales, or 1,166 gallons. Thus, cold room 
space would be needed for 12,826 gallons. 

The number of cases stored would depend upon 
the size of case and container. The 16-quart uni- 
versal case is suggested. It holds 9 half-gallon 
containers (4.5 gallons) or 28 pints (3.5 gallons). 
The case measures 13'14 inches by 13^ inches. 
However, a %-inch clearance allowance is sug- 
gested between stacks of cases. Therefore, storage 
needs should be based on measurements 14 inches 
by 14 inches. 

Based on the assumptions that all of the half- 
and-half (466 gallons) would be packaged in pint 
containers, 70 percent of the milk (7,836 gallons) 
in half -gallon containers, and 30 percent (3,358 
gallons) in quart containers, storage space would 
be needed for 3,005 cases. 

If cases are stored in stacks five high, space for 
601 stacks of cases would be needed. One stack 
would require 1.36 square feet of floor space, and 
601 stacks would require 818 square feet. 

The cold room can be divided into two general 
areas: One for storing a reserve of the finished 
product, and the other for storing the finished 
product made up for retail orders. The first area 
should be located next to the processing and filling- 
room and the other near the retail loadout doors. 
Milk from the reserve area would be moved daily 
into the area for retail order makeup. 

If half the 601 stacks of cases are stored in the 
reserve area for finished products and 20 percent 
of the area is used for aisle and conveyor space, 
512 square feet of space would be needed for this 
area. 

The other half of the -cases are stored in the area 
for making up retail orders. If 50 percent of the 
area is used for aisles and a conveyor and for 
making up orders, the area would require 818 
square feet of space. 

Thus, the plant requires 1,330 square feet of cold 
room space. A room 49*4 feet by 281/2 feet, 1,403 
square feet, is suggested. 

Two sides of the suggested cold room would 
each have three sliding doors located on 10-foot 
centers for loading out retail routes. The doors 
would slide rather than swing to prevent inter- 
ference with the trucks. Four trucks averaging 
50 cases each could be loaded daily from each 
door. Therefore, the six doors would permit load- 
ing 1,200 cases on 24 retail trucks. The remaining 
300 cases would be distributed by wholesale truck 
and would be loaded from the in-floor conveyor 
(25) at the end of the cold room by plant labor. 
Byproducts purchased from outside sources would 
be taken into the order-makeup area for retail 
routes by reversing the conveyor (fig. 6). 

The cold room should be adequately insulated 
to provide economical refrigeration. The floor 




Figure 6. — A typical in-floor conveyor in a cold room. 
Floor is steel diamond plate laid over a concrete base. 
The steel resists wear and makes it easier to slide 
cases of milk off or onto the conveyor. 



should be constructed of concrete covered with 
steel diamond plate. The diamond plate is resist- 
ant to wear and makes it easier to slide stacks of 
full cases off and onto the conveyor or into the 
retail trucks. The floor should be pitched not less 
than 3/16 inch per foot to a trench-type drain 
along each side of the in-floor conveyor. 

The cold room is refrigerated by two direct 
expansion cooling units suspended from the 
ceiling. 

Dock for Loading Retail Trucks 

The cold room should be equipped with docks 
for loading trucks and receiving empty cases. 
The docks should be extensions of the cold room 
floor so that stacks of cases can be dragged across 
them directly onto trucks. On one side of the room 
the dock is iy 2 feet wide. The dock on the end 
and on the other side of the cold room should be 
4 feet wide to provide space for the in-floor con- 
veyor (25) for transporting empty cases from 
wholesale and retail trucks to the empty-case 
storage room. Retail trucks would load at the 
sides of the cold room, and wholesale trucks at the 
end. Five retail trucks can unload empty cases at 
the same time on the dock on one side of the cold 
room. 



13 



The floors of the loading docks- should be 
covered with steel diamond plate to provide easy 
sliding of full stacks into the trucks. 

Storage Rooms 

Separate rooms are provided for storing empty 
cases, paper containers, and miscellaneous dry 
supplies. 

Empty Cases. — The storage room for empty 
cases includes space for the conveyor system and 
the following equipment: an automatic case un- 
st acker (27), capacity 15 cases per minute; a case 
washer (28), capacity 15 cases per minute; a 
supply tank for conveyor lubricant (58) ; and a 
stack feed magazine (26) for the in-floor 
conveyor. 

The maximum number of stacks of empty cases 
stored would be approximately the same as the 
number required to store milk and milk products 
in the cold room — 601. A room 33 feet by 40 feet, 
containing 1,320 square feet of usable space is 
suggested. A space approximately 12 feet wide 
by 22 feet long (264 square feet) would be re- 
quired for the equipment. Based on storing 601 
stacks of cases, allowing 1.36 square feet of space 
per stack and 20 percent of the storage area for 
conveyor and aisles, the total space required for 
storing empty cases is 1,021 square feet. The total 
space needed for equipment and storage is 1,285 
square feet. 

The supply tank (58) feeds soap and water 
lubricating solution to the strands of the conveyor 
chain through pipes that parallel the conveyor 
circuit. 

The automatic case imstacker (27) unstacks 
empty cases from the stack magazine (26) of the 
in-floor conveyor and elevates them to the above- 
floor conveyor (30) (fig. 7). The magazine holds 
200 cases, or about a 23-minute supply for the 
fillers (21 and 22) when they are running at maxi- 
mum capacity. 

The washer (28) cleans the cases before feeding 
them to the automatic casers (23) . 

Paper Containers. — This storage area is de- 
signed for receiving and storing paper containers 
and supplying the cartons to the fillers efficiently. 
It has a dock 4 feet wide for unloading containers 
received by truck. The space requirements for the 
area are determined by the volume and type of 
products handled, the container sizes, the method 
used for stacking containers, and the plant's pur- 
chasing policy. 

It is assumed that the proposed plant would re- 
ceive cartons in truckload lots so as to benefit from 
minimum freight charges. Generally, 360,000 
containers in the ratio of sizes assumed for the 
plant comprise a truckload lot. 

The number of cartons required weekly, for a 
plant processing 35,000 gallons and packaging in 
cartons in the sizes assumed, is 98,500. It is also 
assumed that the plant would maintain at least 
a 2-week supply of cartons for protection against 

14 




Figure 7. — Cases are fed into this end of the automatic 
case unstackers. 

delays in shipments. Thus, the plant would need 
to provide storage space for a total of 557,000 
cartons — a 2-week supply plus a truckload lot. 

This is roughly a B^-week supply. Cartons 
would be received at the plant in fiberboard cases 
on pallets 40 inches square. A pallet holds 32 
cases of half-gallon cartons stacked 8 high, or 
30 cases of either quart cartons or pint cartons 
stacked 5 high. A supply of 557,000 cartons of 
the sizes assumed would require about 46 pallets. 

An 8-inch allowance should be provided between 
pallets to permit adequate air circulation around 
them. It is suggested that the pallets be stacked 
two high on racks. Approximately 368 square feet 
of space would be needed for storing about 46 
pallets, if they are stacked two high. 

A room 27% feet by 23i/o feet, containing ap- 
proximately 652 square feet of space, is suggested 
for storing paper containers. The room should 
have two 5-foot doorways, one leading to the out- 
side dock for receiving cartons, the other for mov- 
ing cartons to the filling machine in the processing 
and filling room. The room should have an aisle 
8 feet wide extending its full length so that a walk- 
behind type of f orklift truck may be used for mov- 
ing cases of cartons on pallets into and out of the 
room. Aisle space would require about 222 square 
feet. The total space required for the 46 pallets 
and aisle is 590 square feet. 

The floor of the room should be of concrete, 
pitched 14 mcn P er f°°t to drains. Walls and 
door should be verminproof and fly tight. 

Dry Storage. — The dry storage room sug- 
gested for the plant is 193/4 feet by 2734 feet. It 
contains about 548 square feet of usable space. 
Here are stored miscellaneous supplies, such as 
washing compounds and surplus cases. The room 
should have the same construction features as the 
paper-container storage room. 



Laboratory and Office Areas 

The suggested laboratory and plant office is 11 
feet by 12 feet, 132 square feet of space. The 
plant foreman keeps his records in this room. 
It houses laboratory equipment for Babcock but- 
terfat tests and bacteriological examination of pro- 
ducers' samples and finished products. The floors 
and walls should be of the same construction as 
those in the processing and filling room. 

A room 11 feet by 14*4 feet is suggested for 
lockers and toilets for plant workers. It can be 
divided into two parts — 94 square feet for a locker 
room, and 63 square feet for a washroom and toilet 
facilities. The suggested locker room provides 
space for 10 workers. 

The main office area measures 33!/2 feet by 44% 
feet, 1,500 square feet of space. This area provides 
space for the manager's office, the general office, a 
room for truck drivers, a locker, and toilets. 

Cleaned-in-PIace Equipment Room 

A room 19y 2 feet by Sy 2 feet, containing 166 
square feet of space, is suggested for an automatic 
CIP unit (31). The room would also provide 
storage space for several days' supply of cleaning 
and sterilizing compounds. 

The automatic CIP unit, through controlled cir- 
culation of cleaning and sterilizing agents, cleans 
equipment parts that come in contact with milk 
or milk products. The basic components of the 
unit include solution tanks, automatic valving to 
provide solution flow paths, and a solution feed 
pump. The unit has three solution tanks, one for 
a rinse, one for an alkali, and one for an acid. 

This unit is part of a cleaned-in-place system. 
Other parts of the system consist of a CIP hookup 
station (32) located in the processing and filling 
room; three CIP solution return pumps (34), one 
located in the processing and filling room, one in 
the tanker-receiving shelter, and one in the area 
for the raw-milk storage tanks; and a CIP trans- 
port tank washer on hoist (33), located in the 
tanker-receiving shelter. 

The hookup station is a device for centrally 
connecting the CIP unit to various items of equip- 
ment to be cleaned. It has a feedline that connects 
to the CIP unit. The feedline connects to several 
other lines leading to different items of equipment 
by means of a swing elbow. 

The solution return pumps return the cleaning 
solutions to the CIP unit for recirculation to the 
spray balls or for storage until needed for other 
equipment. The transport washers are for clean- 
ing tank trucks. 

Refrigeration Equipment Room 

The suggested room contains about 950 square 
feet of usable space for equipment (27% by 34 1 / 4 
feet) and an aisle 8 feet wide and 25 feet long 
for moving machinery in and out as well as for 
personnel traffic. 

The refrigeration equipment consists of the 



sweet- water pumps (41), a 16,000-pound ice 
builder (42), a 15-horsepower (hp.), 12-ton am- 
monia compressor (44), a 15-hp., 10-ton ammonia 
compressor (45), and an ammonia receiver 20 
inches in diameter and 12 feet long (47). (See 
appendix). A 25-ton evaporative condenser (48) 
is located outdoors adjacent to the wall near the 
receiver (47) so that condensed liquid ammonia 
will drain back to the receiver by gravity. 

Other equipment in this room is a 500-gallon 
hot water tank (40) for plant cleanup, a 15-hp. 
air compressor (52) to provide air for equipment 
requiring it, and an electric distribution panel (51) 
including magnetic starters with overload protec- 
tion for each three-phase motor in the plant. The 
electric distribution panel is along one wall with a 
3-foot aisle in front for service work. 

Boiler Room 

The suggested boiler room is 19y 2 feet by 24^ 
feet. It contains 473 square feet. It provides 
space for a 50-boiler-horsepower (b.hp.) steam 
boiler (36) and a system (38) for feeding water 
to the boiler and for returning condensate to the 
boiler. (See appendix.) 

The room provides adequate space at the front 
of the boiler for replacing boiler tubes. The floor 
should be near grade level to provide 3 feet of 
additional head room, which will help to maintain 
good ventilation. The suggested ceiling height is 
17 feet, 

The boiler room should be separated from the 
rest of the plant by a firewall. 

Arrangement of Plant Components 

The processing and filling room is centrally lo- 
cated, with the raw-milk storage area, tanker-re- 
ceiving shelter, CIP room, cold room, empty-case 
storage room, dry storage room, paper-container 
storage room, laboratory and plant office, and re- 
frigeration equipment room grouped around it. 

This location provides for short, direct routes 
for raw milk, paper containers, and empty cases 
to the processing and filling room and for pack- 
aged milk from the processing room to the cold 
room. 

The tanker-receiving shelter is at the rear of 
the plant and adjacent to the raw-milk storage 
area, This location permits trucks to be unloaded 
without interfering with other plant operations 
and minimizes the distance milk is pumped from 
tank trucks to the raw-milk storage area. 

For the greatest efficiency in cleaning tanks and 
processing equipment, the CIP room is located 
near both the tanker-receiving shelter and the 
processing and filling room. 

The cold room is at the center of one side of the 
plant, with three sides of the room accessible to 
route trucks. Empty cases are unloaded at the 
dock on one side of the room, where the in-floor 
conveyor leads directly to the empty-case storage 
room. 

15 



The storage rooms £or miscellaneous supplies 
and paper containers are On the other side of the 
plant; thus, all receiving and loading areas are 
separate. 

The laboratory and plant office, located almost 
in the center of the plant, gives the plant foreman 
an excellent view of processing and filling opera- 
tions. It also provides short distances of travel 
for the worker obtaining samples for tests. 

The locker and toilet room for plant workers is 
next to the plant office and directly off the plant en- 
trance. This entrance is used by the workers: 
it is also used to move equipment in and out of 
the plant. It is located almost in the center of 
the plant so machinery may be moved in and out 
with short distances of travel. 

The refrigeration equipment and boiler rooms, 
at the rear and side of the plant, are isolated from 
the food operations, but their location minimizes 
the amount of piping required to supply utilities 
to major components of the plant, 

The main office is located at the front of the 
plant for the convenience of plant patrons. 

Provision for Plant Expansion 

The layout for the plant shown in figure 1 
provides for a future expansion from 35,000 gal- 
lons to 70,000 gallons weekly. In some compo- 
nents the expansion would necessitate the addition 
of more area, and in others the expansion would 
be made by acquiring more or larger equipment. 
The components of the plant that would require 
more area for the plant to handle 70,000 gallons 
a week efficiently are the cold room, the empty- 
case storage room, the dry storage room, the 
paper-container storage room, and the office. An 
addition of about 4,300 square feet is suggested. 
Thus, the present plant could double its capacity 
with the addition of only 37 percent more usable 
floor space. Excluding office space, the capacity 
of the plant could be doubled by adding only 3,146 
square feet, or 27 percent more space. 

An area 2Sy 2 feet by 491/4 feet, containing 1,404 
square feet, would be added to the cold room, 
doubling its capacity. The location of the cold 
room provides for its expansion without changing 
any other part of the plant. An area 33 feet by 
20 feet, containing 660 square feet, is suggested for 
the empty-case storage room. The dry storage 
room would require the addition of an area 19 3 /4 
feet by 25 feet, containing 494 square feet, and the 
paper-container storage room would require the 
addition of an area 23i/o ^ ee ^' by 25 feet, contain- 
ing 588 square feet. More frequent deliveries 
would reduce the space requirements for both the 
dry storage and container storage rooms. 

The tanker-receiving shelter is adequate for the 
expanded volume. Space is provided in the pres- 
ent raw-milk storage tank area for the installation 
of an additional tank with a capacity of 8,000 gal- 
lons. Thus, the expanded plant would have stor- 
age capacity for 20,000 gallons of raw milk. 



Expansion of the processing area to handle 
70,000 gallons weekly can be made with the fol- 
lowing equipment changes: Replace the 1,000- 
gallon surge tank (19) with a 3,000-gallon surge 
tank; step up the HTST system to 2,000 gallons 
per hour (g.p.h.) ; exchange the separator-clarifier 
(9) for a unit that will separate 10,000 pounds of 
cold milk per hour and clarify 18,000 pounds per 
hour; and install an additional 400-gallon half- 
and-half vat. 

Spaces are provided in the control panel for 
the additional equipment. These spaces are indi- 
cated by dotted lines in the diagram of the control 
panel (fig. 11, page 21). Space in the processing 
and filling room is adequate for the additional or \ 
larger sizes of equipment suggested. 

A half-gallon filler that would fill 72 cartons per I 
minute, compared to the present unit's rate of 33 
cartons per minute, could be installed. The pres- 
ent quart-pint filler (21) should be adequate, 

When the volume of the plant approaches 70,- 
000 gallons weekly, another CIP unit (54) will 
be needed for performing operations efficiently. 
This additional unit would be for cleaning raw- 
milk equipment only. When the additional auto- | 
matic CIP unit is installed, it will also be 
necessary to install another control panel. This 
control panel should be located beside the main 
control panel (1) in the processing and filling 
room. 

The case washer (28) and automatic case un- 
stacker (27) are large enough to handle the fu- 
ture requirements of the plant. 

Xo expansion is required in the laboratory and j 
plant office or in the locker or toilet room. 

Space is provided in the refrigeration equip- 
ment room for a future ice builder (43) and fu- 
ture ammonia compressor (46). Another evapo- 
rative condenser (49) can be placed outside of the 
room. Adding this equipment will double the re- 
frigeration capacity. The boiler room has space 
for another steam boiler. 

Plant Site 

The plant site should be large enough to pro- 
vide for the building, driveways to public high- 
ways or major city thoroughfares, parking for 
plant trucks and customers, a maintenance ga- 
rage, gas island, and future expansion. The site 
should be convenient to the area it serves. The 
site should be fairly level and well drained and 
should have easy access to an ample water supply, 
electrical power, and sewer facilities. 

The plot plan for the plant is shown in figure 8. 
The building is located on a site 330 feet wide and 
360 feet deep, roughly 2.7 acres. This width and 
depth cannot be materially decreased if the sug- 
gested plant layout is to be used. Irregularly 
shaped sites should be avoided if possible. The 
plant proper comprises approximately 11,573 
square feet and is located almost in the center of 
the site. It is suggested that four areas, two 



16 



PFF 



EXPANDED 
PAPER CONTAINER 
STORAGE - 




SCALE OF FEET 
20 40 



Figure 



A suggested layout of a site for a special-purpose milk plant handling 35,000 gallons of milk weekly. 
Dotted lines show the provisions made for expansion. 



directly in front of the building and one at each 
side, comprising about 16,000 square feet, be land- 
scaped. A 34- by 50-foot garage for repairing 
and servicing plant trucks also is suggested. The 
garage should be located to the rear and at one 
side of the property. 

Two paved driveways would connect the plant 
with the highway. One driveway would be 30 
feet wide and one 40 feet wide. Aprons con- 
necting with the major docks of the plant should 
be not less than 70 feet wide and should have 
paved surfaces. 

Well-defined offstreet parking areas should be 
^provided on the site for 56 motor vehicles. These 
areas should be out of the traffic lanes but easily 
accessible from them. The parking areas should 
be paved and well drained. Individual spaces 
for 31 automobiles should be 11 feet wide and 22 
feet deep, and for 25 trucks, 12y 2 feet wide and 
25 feet deep. All truck space should have electric 
plug-in lines to provide electrical power to op- 
erate the mechanical refrigeration equipment in 
each truck. 



Schedule of Equipment Use 

Equipment selected for the plant is sized to 
meet the requirements of the daily processing 
schedule efficiently and economically. 

The schedule of equipment use (fig. 9) for the 
peak processing day of the week shows the time 
periods necessary for receiving and processing- 
milk and cleaning equipment. On the peak day, 
7,200 gallons of market milk and 300 gallons of 
half-and-half are processed. 

Receiving and Processing 

At the beginning of the day about 940 gallons 
of the 4,000 gallons of milk with a butterfat con- 
tent of 3.8 percent held over from the previous 
day in tank (4) would be separated. Separation 
would begin about 6 :30 a.m. and continue to about 
8 :00 a.m. The skim milk would be diverted to 
tank (6) for standardizing and the 15-percent 
fat product would be diverted to the half-and-half 
vat (10). 

17 



Receiving of raw milk would begin about 7 :00 Raw milk with a butterfat content of 3.8 percent 

a.m. and continue intermittently until about 10 :00 would be standardized to 3. 5-percent butterfat for 

a.m. About 3,500 gallons would be received in market milk by pumping skim milk from tank 

tank (5), and 500 gallons in tank (4). Pump (2) (6) to the raw milk in tanks (4) and (5). This 

would be used for receiving milk. standardization would require about 15 minutes 



EQUIPMENT 



6A.M. 7 



HOUR OF DAY 

10 II 12 I 2 



6PM. 



TANK (4) 

TANK (5) 

TANK (6) 

VAT (10) 

SEPARATOR-CLARIFIER (9) 

PUMP (7) 

PUMP (8) 

HTST SYSTEM (12 THRU 18) 

SURGE TANK (19) 

SURGE TANK (20) 

1/2 GALLON FILLER (22) 

QUART-PINT FILLER (21) 

CLEAN SANITARY LINES 



jT b PEMJj 



u 



r_t 



i en 



U 



B_J 



I I 



?f 



np 

IE 



SJ 



m 



u 



m 



L^ 



Qj 



I R 1 s I 



LEGEND 



RECEIVE 3.8% MILK. 
SEPARATE 3.8% MILK. 
SEPARATED 0.1% SKIM. 
SEPARATED 15% FAT PRODI 
STANDARDIZE 3.8% MILK 
TO 3.5% MILK. 

STANDARDIZE 15% FAT PR0DUC 
TO 11% HALF 8 HALF. 
CLARIFY 3.5% MILK. 
PROCESS 3.5% MILK. 
PROCESS 11% HALF a HALF. 



J. 


HOLD 3,8% MILK. 


K. 


HOLD 3.5% MILK. 


L. 


HOLD 0.1% SKIM. 


T. M. 


HOLD 15% FAT PRODUCT. 


N. 


HOLD 11% HALF a HALF. 


0. 


FILL 3.5% MILK. 


CT P. 


FILL 11% HALF a HALF. 


Q. 


CLEAN EQUIPMENT. 


R. 


RAW LINES. 


S. 


PASTEURIZED LINES. 



Figure 9. — Assumed schedule for a peak processing day (7,500 gallons) for a special-purpose plant handling 35.000 

gallons of milk weekly. 

18 



for each tank. Although 7,700 gallons of market 
milk would be standardized, only 7,200 gallons 
would be pasteurized and packaged; 500 gallons 
of standardized milk would remain in tank (5). 
(From a practical operating standpoint this 500 
gallons also would be pasteurized and packaged.) 

The 200 gallons containing 15-percent butterf at 
in vat (10) would be standardized to 11-percent 
half-and-half between 9 :25 a.m. and 9 :35 a.m. and 
held in the vat until 2 :10 p.m. for further process- 
ing. Pump (7) would transfer skim milk from 
tank (6) to vat (10). 

In this report clarifying is considered a part 
of the pasteurizing and homogenizing operations. 
These operations would begin about 9 :00 a.m. for 
market milk and continue until approximately 
2:30 p.m. — a total of 5 hours and 30 minutes. 
Tank (4) would supply raw standardized milk 
for processing from 9 :00 a.m. to 11 :45 a.m. and 
tank (5) would supply it from 11:45 a.m. to 2:30 
p.m. Processed market milk would flow to surge 
tank (19). 

Half-and-half would be processed between 2 :30 
p.m. and 2:45 p.m. It would flow to surge 
tank (20). 

Filling Cartons 

After pasteurization and homogenization begins 
at 9 :00 a.m., processed market milk begins to ac- 
cumulate in surge tank ( 19 ) . The half-gallon fill- 
ing machine (22) would be started at 9:30 a.m., 
and the quart-pint filling machine (21) an hour 
later. The total filling time for market milk is 
about 5 hours and 5 minutes. The two filling 
machines would operate simultaneously for only 
3 hours and 15 minutes. 

Filling operations for half-and-half would be 
from 2 :35 p.m. to 3 :30 p.m. Half-and-half would 
flow from surge tank (20) to quart-pint filler (21) . 

How the Plant Operates 

Some plant operations are controlled from the 
control panel. Other operations are mechanized or 
manually controlled. Only major operations per- 
formed in the receiving, processing, packaging, 
and handling of milk are discussed. Figure 10 
illustrates product flow. Such operations as re- 
ceiving empty paper containers, which are per- 
formed periodically, making laboratory tests, or 
maintaining the refrigeration or heating systems 
are not discussed. 

Control Panel Operations 

The suggested control panel for the plant is 
shown in figure 11. Each number on the control 
panel is the same as the number of the equipment 
it controls. The numbers of the various items of 
equipment are shown on the suggested layout 
(%1). 

Pushbutton (1) on the control panel supplies 
power to instruments in the control panel. 



The various features of the control panel are 
discusssed by major operations: Receiving raw 
milk; separating; standardizing; pasteurizing and 
homogenizing; agitator and refrigerant controls; 
flow of milk and milk products to filler bowls ; and 
cleaning-in-place equipment. 

Receiving Raw Milk 

After the worker has connected the sanitary hose 
of the receiving pump (2) to the tank truck outlet, 
the receiving operation is conducted from the con- 
trol panel. 

A "Raw fill" switch and a button just below it 
on the control panel control the flow of milk from 
tank truck to each of the storage tanks (4, 5, or 6) . 
A tank is selected on the "Raw fill" switch and the 
button is pushed to start the receiving pump and 
to arrange the air-operated valves in the manifold 
system in front of the tanks so that milk will flow 
into the tank selected. The valves in the manifold 
system are interlocked so that if the tank selected 
and the line to it are already in use, the valve will 
not open. This eliminates the possibility of mix- 
ing milk of different butterfat content. 

Three minutes before a tank is full, an alarm 
sounds to warn the operator, and a red light just 
above the "Raw fill" selector switch comes on. The 
operator can stop the alarm and shut off the red 
light by pressing the "Alarm stop" button just to 
the right of the red light, and he may select 
another tank. If the "Alarm stop" button is not- 
pressed by the end of 3 minutes, the receiving 
pump automatically stops and the inlet valve of 
the raw-milk storage tank closes. 

Pump No. 2 pushbuttons on the control panel 
are used for starting and stopping the receiving 
pump if the automated system is not functioning 
properly. 

In the lower left-hand corner of the control 
panel are a weight selector switch and a weight in- 
dicator for determining the amount of milk in any 
one of the three raw-milk storage tanks. To deter- 
mine the amount of milk in a particular tank, 
the operator turns the selector switch to the tank. 
The indicator above the switch will show the 
weight in number of pounds. If milk is to be 
added to a partially filled tank and the weight of 
the added milk is desired, weight readings must 
be taken before and after the milk is added. 

Individual weight readings of each tank must- 
be made to determine the total amount of milk 
in all tanks. The total weight indicator and selec- 
tor switch on the panel are used to automatically 
add a specified amount of milk to a tank. (See 
Standardizing, p. 22.) 

Temperatures of all raw milk products in the 
storage tanks and the 400-gallon half-and-half vat 
(10) are recorded on a "Raw milk recorder" in 
the upper left-hand corner of the control panel. 

Separating 

The separator-clarifier (9) is adjusted to sepa- 
rate raw milk into skim milk and a product with 



665977 0—63- 



1.9 



15-percent butterfat content. The 15-percent 
butterfat product is pumped to the half-and-half 
vat (10), and the skim milk is diverted to a raw- 
milk storage tank. 

In separating raw milk automatically, the opera- 



tor turns the "Raw empty" switch on the control 
panel to the number of the tank from which milk 
is to be taken and pushes button No. 9 to start the 
separator (9). The positive displacement trans- 
fer pump (8) is run momentarily to provide milk 



\3,/ 

RECEIVE a STANDARDIZE^ 

TO HTST 
SKIM a TRANSFER 



(FUTURE^ 
* 400 ' 




LEGEND 

-§- <j>- 3 WAY UNE OR MANIFOLD VALVE 
~0- 2 WAY OUTLET OR STOP VALVE 

)|ta 2 WAY THROTTLING VALVE 

b- CENTRIFUGAL PUMP 

POSITIVE DISPLACEMENT PUMP 



Figure 10. — Product now from tank trucks to filling machines in the plant handling 35,000 gallons of milk weekly 
20 




o 



s> 







a. 




8 


















UJ 






+ 




K 

5 






^ 




5 










3* 








1 





o o 
z z 

UJ UJ 
Q O 

©e 



21 



for lubricating the separator seals; pushbutton No. 
8 starts and stops the pump. When the separator 
is up to proper speed, the raw-milk storage tank 
into which skim milk is to be diverted is selected 
on the control switch called "Skim to transfer 
from." Button No. 8 is then pushed again to start 
transfer pump No. 8 and begin the separation of 
milk. 

The raw-milk storage tanks are equipped with 
alarms which sound when the level of milk drops to 
500 pounds. This allows the operator 51/2 minutes 
to select, another raw-milk storage tank if more 
milk is needed or stop the separation by turning 
the "Raw empty" switch to "off." 

The total amount of milk withdrawn from a 
tank can be determined by taking weight readings 
on the tank before and after separating. Since 
the weight selector switch is also connected to the 
half-and-half vat, the amount of 15-percent butter- 
fat product separated also can be determined. 

Standardizing 

Market Milk. — Raw milk of 3.8-percent but- 
terfat is standardized by adding sufficient skim 
milk to bring the butterfat content to 3.5 percent. 
The skim milk used tests 0.1-percent butterfat. 
Both the raw milk and the skim milk would be 
held in raw-milk storage tanks; standardization 
would take place by pumping the skim milk into 
the tank with the raw milk. 

The raw milk in the tank is first weighed in the 
manner previously described. A sample of milk 
is taken from the cock in the manhole cover of 
the tank and tested for butterfat content in 
the laboratory. The operator then determines 
the amount of skim milk needed for standardizing 
the raw milk by consulting a chart and adds the 
weights of the skim and raw milk to obtain the 
total weight of the milk when standardized. The 
weight is set on the "Total weight" indicator by 
turning the perimeter knob around the indicator. 

The tank selector switch below the total weight 
indicator is set to the number of the tank in which 
the raw milk to be standardized is held. This 
connects the total weight indicator to the load 
cells under the tank. The number of the skim- 
milk tank is set on the selector switch "Skim to 
transfer from," the number of the raw-milk tank 
is set on the selector switch "Transfer to," and the 
button beneath the "Transfer to" selector switch 
is pushed. Pushing this button opens the inlet- 
outlet valves on both the raw-milk and skim-milk 
tanks, sets the air-operated valves in the manifold 
in front of the tanks in the proper positions to 
transfer skim milk to the raw milk, and starts the 
transfer pump (7). If the agitator in the raw- 
milk storage tank is on when the button is pushed, 
it automatically turns off. 

When the weight in the raw-milk tank reaches 
the weight set on the total weight indicator, trans- 
fer pump (7) automatically stops, valves to the 
tanks close, and the agitator in the raw-milk tank 
starts automatically. After the milk is agitated 

22 



for 10 minutes, a green pilot light indicates that I 
standardization process is complete. The oper- ;r 
ator turns the "Transfer to" selector switch to I 
"off." A butterfat test would be made at this 
point. If test is unsatisfactory, more skim or more 
raw milk is added. The procedure for making the 
addition would be the same as described above. 

The centrifugal transfer pump (7) can be 
operated manually with the pushbutton on the I 
control panel if the automated system fails to 1 
function properly. When this pump is operated . 
manually, the air-operated valves would have to 
be manually controlled. 

Half-and-half. — Eleven-percent half -and-half 
would be made up in the half-and-half vat (10) 
by mixing skim milk with the 15-percent butter- 
fat product. The amount of skim milk required 
is determined and added to the 15-percent butter- | 
fat product in the same manner as described for 
adding skim to raw milk. 

Pasteurizing and Homogenizing 

In the automated HTST system, pasteurization I 
and homogenization are programed to occur as I 
one continuous operation, beginning with the clar- 
ification of raw standardized milk. 

The first step is to select the surge tank (19 or 
20) for pasteurized and homogenized market milk 
or half-and-half, turn the HTST "Discharge to" 
switch to the tank number, and push the button 
just below the switch to open the tank's inlet-outlet 
valve. 

The second step is to turn the "Raw empty" 1 1 
switch to the number of the tank containing 
standardized raw milk and the "Master selector" 
switch to "Process." This aligns the valves in the 
sanitary lines to deliver raw standardized milk to jlj 
the pasteurizing and homogenizing equipment, i 
The operator manually sets the separator-clarifier 
(9) to clarify by adjusting a valve on the machine. 

The third step is to start up the HTST system 
by pushing the button on the "Raw empty" selec- I 
tor switch. This opens the inlet-outlet valve on 
the raw-milk storage tank and starts the positive I 
displacement pump (8) to pumping milk through I 
the clarifier (9) and to the balance tank (12). | 
When milk coming into the balance tank from the 
clarifier rises to the height of the low-level probe, 
the probe automatically causes the positive dis- 
placement timing pump (15), hot water pump 
(50), sweet- water pump (41), and vacuum and 
water removal pump and water level control for 
the UHTH system to start, 

Pump (15) draws milk from the balance tank 
through the regenerative section of the plate heat 
exchanger, where its temperature is raised from 
40° F. to 140°. The pump then forces the milk 
to the heating section where its temperature is in- 
creased to 170°. From the heating section, milk 
flows through the holding tube, where it is held 
at that temperature for 16 seconds. It then passes 
to the flow diversion valve. 

If the temperature of milk as it reaches the di- 



version valve is above 161° F. (legal pasteurizing 
temperature) , a relay in the HTST recorder-con- 
troller opens the incoming steam line to start the 
steam infuser, the vacuum cylinder, the product 
removal pump, and the homogenizer (18) under 
no-load conditions, and milk passes to the steam 
infuser. If the temperature of milk is below 161° 
as it reaches the diversion valve, the valve auto- 
matically returns it to the balance tank for recircu- 
lating and reheating. 

To maintain a constant supply of milk in the 
system, the balance tank operates in the following 
manner : When milk coming into the tank from 
the clarifier and from the diversion valve rises to 
the height of the high-level probe in the tank, the 
probe automatically cuts off pump (8). This, in 
effect, cuts off the supply of milk coming from the 
raw-milk storage tank and prevents the balance 
tank from overflowing. When the supply of milk 
in the balance tank drops to the low-level probe, 
the probe automatically starts pump (8) to pump 
cold milk through the clarifier to the balance tank. 

Cold milk in the balance tank is fortified with 
vitamin concentrate from the vitamin feed cabinet 
(13). Vitamin concentrate is automatically 
metered into the tank only when pump (8) is oper- 
ating and raw milk is being pumped into the tank. 

From the flow diversion valve, milk passes to 
the steam infuser section of the UHTH (ultra- 
high-temperature heater) system. 

The infuser injects culinary steam into milk and 
heats it from 170° F. to a preset temperature in 
the range of 196° to 210° . The milk then passes to 
the vacuum cylinder section of the UHTH heater 
where it is immediately cooled, as a result of the 
drop in pressure, to 166°, or about 4 degrees be- 
low the temperature at which it enters the UHTH 
system. This insures that slightly more water is 
removed by evaporation than is added by steam. 

The ratio- recorder controller modulates the tem- 
perature the milk attains in the ultra-high-temper- 
ature heater system to whatever temperature is 
selected on the controller. It also records the tem- 
perature of milk on a chart. 

Milk is pumped from the vacuum cylinder to 
the homogenizer (18). 

Milk first flows through the homogenizer, under 
no-load conditions, to the regenerative and cooling- 
sections of the plate heat exchanger, where its 
temperature is decreased from 166° F. to 38°, and 
from the cooling section to a three-way valve in 
the system. Since the milk is not homogenized, 
the three-way valve diverts it back to the balance 
tank. When milk first hits the three-way valve, 
a pressure switch actuates the homopressure con- 
troller. The homopressure controller controls a 
diaphragm mounted on the stem of the homoge- 
nizing valve of the homogenizer, and the dia- 
phragm automatically raises the pressure of the 
homogenizer to load conditions. After the ho- 
mogenizer has operated under load conditions for 
a preset time, the three-way valve automatically 



diverts homogenized milk that has passed through 
the cooling section to surge tank (19). 

To stop the HTST system the "Raw empty" 
selector switch is turned off. This stops pump 
(8) and the flow of milk from the raw-milk stor- 
age tank. To close the system down, the "Raw 
empty" selector, the "Master selector" switch, and 
the "HTST discharge to" switch would be turned 
off. fe 

Pushbuttons 50, 41, IT, 18, and 15 are used to 
operate any of the various pieces of equipment 
manually with the "Master selector" set to "off." 

Half-and-half in vat (10) would be pasteurized 
and homogenized by the same procedure, with the 
selector switches set on the appropriate tanks and 
vats. 

Agitator and Refrigerant Control 

Agitation is done automatically only during the 
standardizing of market milk and half-and-half. 
Pushbuttons (4), (5), (6), (10), (19), and (20) 
in the control panel under "Agitator tank No." 
are for starting and stopping the agitation in the 
raw-milk storage tanks, the half-and-half vat, and 
the surge tanks. 

Pushbuttons (4), (5), (6), and (10) on the 
control panel under "Refrigerate tank No." con- 
trol the circulation of 34° F. sweet water through 
the refrigerated surfaces of the raw-milk storage 
tanks and the half-and-half vat. These controls 
operate the electric circuit to actuate the solenoid 
valves, which admit sweet water to the refriger- 
ated surface. Operating any one of these circuits 
also causes the sweet-water pump (41) to start. 

Flow of Milk and Milk Product to Fillers 

Market milk flows through the fillers first, fol- 
lowed by half-and-half. Products from surge 
tanks (19 and 20) are forced through sanitary 
lines to the fillers by air pressure. A pressure of 
approximately 5 pounds is maintained in these 
tanks during filling operations. The air com- 
pressor should be equipped with intake filters 
to assure air free from dust and other impurities. 
The air compressor line should be equipped with 
traps to keep moisture and foreign products from 
entering the milk products. 

Market milk flows from surge tank (19) to the 
half-gallon filler (22) or quart-pint filler (21). 
Setting the selector switch "Tank No. 19" on 
"Feed" opens the inlet-outlet valve on the 1,000- 
gallon surge tank (19) and permits the milk to 
flow through a sanitary line to the fillers. Setting 
selector switches "Filler No. 21" and "Filler No. 
22" on tank 19 opens the inlet valve to the fillers. 
The half-gallon filler can be fed only from the 
1,000-gallon surge tank as the half -gallon filler is 
used only on homogenized milk. 

Half-and-half flows from the 600-gallon surge 
tank (20) to the quart-pint filler (21). Setting- 
selector switch "Tank No. 20" on "Feed" opens the 
inlet-outlet valve on the 600-gallon surge tank and 
permits the half-and-half to flow through a sani- 



23 



tary line to the filler. Setting selector switch 
"Filler No. 21" on tank 20 opens the inlet valve 
to the filler. 

Cleaned-in-Place Equipment 

The control panel contains a "CIP program 
controller,'' a "CIP recorder controller," and two 
switches — a "Master selector" and a "CIP selec- 
tor" — for automatic cleaning of equipment in 
place. The switches are for selecting the items of 
equipment to be cleaned and also the type of clean- 
ing operation to be performed — rinse, alkali wash, 
or acid wash. 

The cleaning process for each tank or vat is pro- 
gramed on the program controller so that the 
elapsed time, circulating temperature, and proper 
valve sequencing for each cleaning operation are 
automatically set. The controller is kept locked 
to prevent unauthorized alteration of the cleaning 
cycles. 

The CIP recorder-controller instrument on the 
control panel records the time of the cycle and the 
temperature and pressure of the CIP solutions 
used in each cleaning operation. It also maintains 
a record of the cleaning operations for review by 
management and regulatory agencies. 

Cleaning and sanitizing solutions for the auto- 
matic CIP unit (31) are made up manually by 
adding the proper amount of reagent to the solu- 
tion tanks at the beginning of each day. 

To clean transport tanks, washer (33) is lowered 
into the truck tank and the hose from the tank out- 
let is connected to CIP solution return pump (34) . 
The "CIP selector" switch is turned to "Tanker", 
and the button just below the switch is pushed. 
This starts the cleaning process, which consists of 
rinse, alkali wash, rinse, and sanitize. 

To clean the 4,000-gallon milk storage tanks 
(4, 5, 6), or the 400-gallon half-and-half vat (10) 
the "CIP selector" switch is set to the proper tank 
number. The connection for returning the CIP so- 
lution to the unit is made by hooking a swing elbow 
from the inlet-outlet valve on the tank to a line 
leading to one of the CIP solution return pumps 
(34). The cycle would be similar to that used 
for tank trucks, except that the final sanitizing 
rinse would be omitted. 

To clean the milk lines between the tank truck 
and the storage tanks (4, 5, 6) as well as the mani- 
folds in front of the tanks, the "Master selector" 
switch is turned to "Clean raw lines." Several 
hose jumpers are hooked up to complete the cir- 
cuit, and the pushbutton under "CIP selector" 
switch is pushed. These lines are cleaned in a 
manner similar to that used for the tanks and vat. 
The air-operated sanitary valves are cycled on and 
off by a valve sequencer. 

The HTST system (except for pumps Nos. 8 
and 15, the separator-clarifler, and the homoge- 
nizer) and the surge tanks for pasteurized milk 
would be cleaned in the same manner as the raw- 
milk lines, with the "Master selector" switch set 
to "Clean HTST" or "Clean pasteurized tanks." 

24 



The lines for pasteurized milk are cleaned when 
the HTST system is cleaned. For the portion of 
the HTST system used for hot milk, an acid wash 
is used in addition to the alkali wash. 

Other Operations 

Other operations for the purposes of this report 
are limited to filling cartons and putting them in 
cases, storing cases and making up orders in the 
cold room, loading out milk and milk products, re- 
ceiving, storing, and handling empty cases, and 
manual cleaning of equipment. 

Filling and Casing Cartons 

Since the fillers suggested would utilize plastic- 
coated cartons, no wax, glue, or staples are re- 
quired. The magazine on each filler holds a case 
of cartons. Loading the magazine in case lots 
enables the operator to devote a large portion of 
his time to the inspection of cases (discarding 
damaged or soiled ones) and making adjustments 
on the machines as needed. Both fillers are 
equipped with air-operated throttling valves, 
which shut off the milk supply when the filler stops. 

The above-floor conveyors (30) and the auto- 
matic case divider (29) feed empty cases from the 
storage room to the fillers at the rate required 
for each filler. Filled cartons are transported to 
automatic casers (23) on carton conveyors (fig. 
12).- 




Figure 12. — A carton conveyor carries filled cartons to this 
automatic caser. 



The casers (23) automatically place the filled 
cartons into cases. Each caser has a capacity of 
100 cartons per minute. The automatic caser (23) 
used with the quart-pint filler (21) can be changed 
to multitiering of cartons by turning a switch. 
Multitiering is required when a layer of 12 pints 
is placed on top of a layer of 16 pints in a case. 

Cases of milk are conveyed on above-floor con- 
veyors (30) to the case stackers (24). These ma- 
chines automatically stack cases five high at the 
rate of four to five cases per minute (c.p.m.). 
The stacks then descend, via above-floor conveyor 
(30), to the in-floor conveyor (25) located in the 
cold room. 

Storing Reserves and Making Up Orders 

As previously stated, the cold room is divided 
into two general areas— one for storing a reserve 
i>f the finished product and one for storing the 
finished product made up into orders for retail 
routes. The sizes of the areas depend on the vol- 
ume of the reserve supply. Cases of milk in stacks 
five high are moved through the middle of the cold 
room on the in-floor conveyor (25). A worker 
frags each stack from the conveyor and places it 
in a predetermined location. When orders are 
made up from the reserve supply, a worker drags 
the stacks onto the conveyor, which transports the 
stacks to the area where orders are assembled. 

Loading Out Milk and Milk Products 

Drivers of the retail route trucks load their own 
:rucks. Consequently, no plant labor is used for 
[his operation. 
Receiving, Storing, and Handling Empty Cases 

Drivers of retail route trucks drag stacks of 
3mpty cases onto the in-floor conveyor (25) on the 
lock outside the cold room. The stacks are auto- 
matically conveyed into the empty-case storage 
room, where a worker drags them from the con- 
veyor and stores them. 

Just before the filling of cartons begins, the 
vorker in the empty-case room places stacks of 
3ases on the in-floor conveyor stack magazine (26) . 
From the magazine the cases are conveyed to the 
uitomatic case unstacker (27), then to the case 
vasher, then to the automatic case divider, and 
finally onto the automatic casers. Use of the mag- 
izine gives the operator time to perforin other 
juties while the empty cases move to the fillers. 
Manual Cleaning of Equipment 

Machines that require manual cleaning are the 
positive displacement pumps (8 and 15), the sep- 
irator-clarifier (9), the homogenizer (18), the 
dowIs on the fillers (21 and 22), the balance tank 
[12), the flow diversion valve, and the line be- 
tween them. These machines are disassembled 
md the parts placed in the portable washer (35). 
Hie washer pumps heated washing solutions 
iround the disassembled parts. After being 
leaned, the parts are rinsed with fresh water and 
illowed to dry. The machines are assembled the 
lext day. 



Equipment normally is cleaned manually either 
during the time when the automatic CIP cleaning 
is underway for the circuit in which the equip- 
ment is used or as fill-in work. Practically all 
plant workers participate part time in these op- 
erations. 

Labor Requirements 

Seven workers, other than the office crew and 
route truck drivers, would be required to operate 
the automated plant, four fewer workers than 
would be required in a nonautomated plant han- 
dling a similar volume. Part of the reduction in 
the number of workers in the automated plant is 
due to labor-saving and standardized procedures 
and part is clue to mechanized equipment which 
requires fewer workers or permits workers to per- 
form additional duties. 

The crew for the automated plant consists of a 
supervisor, a relief man, a maintenance worker 
(who also operates the refrigeration and heating 
system), and four other workers. The four work- 
ers, with some assistance from the supervisor, per- 
form all the basic operations required in receiving, 
processing, packaging, and storing milk and re- 
ceiving and handling empty cases and containers. 

A nonautomated plant would require a super- 
visor, a relief man, a maintenance worker, and 
eight other workers. The supervisor would not 
have time to assist workers performing basic op- 
erations in the nonautomated plant. 

In the automated plant, the supervisor and the 
worker who performs the receiving operation 
would also perform the processing operations 
(separating, standardizing, and HTST pasteuri- 
zation). A nonautomated plant requires a full- 
time worker for the processing operations plus the 
assistance of the worker who performs the receiv- 
ing operation. Thus, the automated plant would 
require roughly one man less to perform the proc- 
essing operations than the nonautomated plant. 
This reduction in labor is the result of automation 
in both the receiving and processing operations. 
This saving in labor is predicated on a volume of 
7,500 gallons and one run of milk followed by one 
run of half-and-half. In plants with more com- 
plicated runs, or runs requiring a greater change 
in the use of equipment, a larger saving in labor 
should be realized. 

One worker is required for the packaging, cas- 
ing, and stacking operations in an automated 
plant, compared with three workers in a nonauto- 
mated plant. That two less workers are required 
in the automated plant is due primarily to the use 
of automatic casers (23), automatic case stackers 
(24) , and automatic case dividers (29) . 

One worker would be required to store milk 
and make up orders in both the automated and 
the nonautomated plant. 

One worker would be needed to receive, store, 
and handle empty cases and dry supplies and per- 
form other work in this connection in the auto- 



25 



mated plant ; two workers would be needed in the 
nonautomated plant. This saving in labor is the 
result of the use of the stack feed magazine (26), 
automatic case unstacker (27), and an automatic 
case divider (29). 

Nine workers devote part of their time to clean- 
ing equipment in the nonautomated plant, com- 
pared to five workers in the automated plant. 
Furthermore, the five workers devote considerably 
less time to the job than the workers in the non- 
automated plant. The automated cleaned-in- 
place system makes this reduction possible. 

Estimated Equipment Costs 

The equipment required for the automated 
plant to minimize labor requirements would con- 
sist of a control panel (1), remotely controlled 
sanitary valves, load cells, automatic casers (23), 
automatic case stackers (24), automatic case un- 
stacker (27), stack feed magazine (26), automatic 
case divider (29), and automatic CTP unit (31). 
The estimated cost of the equipment would be 
$85,000 greater than the cost of the equipment 
required for a nonautomated plant. 

Possible Benefits From Labor-Saving 
Devices 

It is estimated that the automated special-pur- 
pose milk plant handling 35,000 gallons weekly 



could operate with at least four fewer workers 
than a comparable nonautomated plant. Based 
on an assumed cost of $6,500 annually per worker 
(salary plus fringe benefits), the reduction in 
labor costs would amount to $26,000. If 20 percent 
of the cost of the equipment is allowed annually 
for owning and operating the equipment (depre- 
ciation, maintenance, interest, insurance, and 
taxes), the cost would be $17,000, and an annual 
saving of $9,000 would result. The saving should 
amortize the cost of the equipment in about 9y 2 
years. 

Production per man-hour of labor should be 
higher in the automated plant. It is estimated 
that on a peak production day (7,500 gallons), the 
production would be 134 gallons of milk per man- 
hour for the automated plant and 85.3 gallons per 
man-hour for the nonautomated plant. Based on 
the w r eekly production of 35,000 gallons, the pro- 
duction per man-hour for the automated plant 
would be 125 gallons per man-hour and 79.5 gal- 
lons per man-hour for the nonautomated plant. 
Roughly, the production per man-hour is 57.2 per- 
cent greater in the automated plant handling 
35,000 gallons of milk weekly than in a nonauto- 
mated plant. 

Machine-controlled operations should reduce 
the in-plant losses of milk. They should also pro- 
vide for more stable standards than are obtained 
in a nonautomated plant using conventional meth- 
ods. No data are available for estimating the 
savings for these items. 



Plant Handling 105,000 Gallons of Milk a Week 



The objectives of developing principles and cri- 
teria for use in planning new or remodeling old 
special-purpose milk plants with automated meth- 
ods for a plant handling 105,000 gallons of milk 
weekly are the same as those listed for the plant 
handling 35,000 gallons weekly. 



The amount of finished products held over on 
Tuesday for Wednesday's and Thursday's distri- 
bution is 35,000 gallons. The peak raw milk hold- 
over is 12,000 gallons. The plant should be de- 
signed with adequate storage tank capacity and 
cold-room storage space for these quantities. 



Assumptions With Respect to Plant 
Operations 

The assumptions used herein are the same as 
those used for the smaller plant. 

The inventory schedule for the plant is shown in 
table 2. Eaw milk receipts are at a peak on Fri- 
day for this plant. The receipts vary from 20,000 
gallons to 12,000 gallons. Distribution of finished 
product is evenly divided over a 6-day period — 
Monday through Saturday — at 17,500 gallons 
daily. Since the plant processes milk only 5 days 
a week, the plant must have sufficient capacity to 
process enough products on Monday and Tuesday, 
plus the carryover, to handle 3 days' sales. The 
amount of production needed on these 2 days is 
22,500 gallons — 21,600 gallons of market milk and 
900 gallons of half-and-half. 



Suggested Layout of the Plant 

The suggested layout for the plant handling 
105,000 gallons of milk weekly is shown in figure 
13. The basic principles observed in arranging 
the various components are the same as those used 
for the smaller plant. 

The suggested building is irregular in shape. 
Roughly its depth is 177 feet and its greatest 
width is 279 feet. It provides approximately 
32,318 square feet of space. 

Components of the Facility 

Figure 13 shows the components suggested for 
the plant and each item of equipment suggested 
for each component. The components are the 
same for this plant as for the plant handling 



20 



Table 2. — An assumed inventory and processing schedule for a plant handling 105,000 gallons of 

milk loeekly 



Milk inventory 


Mon. 


Tues. 


Wed. 


Thurs. 


Fri. 


Sat. 


Sun. 


Beginning raw milk inventory 


Gal. 
12, 000 
17, 000 


Gal. 
6, 500 
16, 000 


Gal. 

12, 000 


Gal. 
12, 000 
12, 000 


Gal. 

4,000 

20, 000 


Gal. 

4,000 

16, 000 


Gal. 




Raw milk receipts ' 


12 000 


Total 




29, 000 


22, 500 


12, 000 


24, 000 


24, 000 


20, 000 


12 000 


Processed milk: 2 
Market milk 




21, 600 
900 


21, 600 
900 






19, 200 
800 


19, 200 
800 


19, 200 
800 





Half-and-half 





Total 




22, 500 


22, 500 





20, 000 


20, 000 


20, 000 





Raw milk holdover 




6, 500 
17, 500 
30, 000 




17, 500 

3 35, 000 


12, 000 
17, 500 
17, 500 


4, 000 
17, 500 
20, 000 


4,000 
17, 500 

22, 500 



17, 500 
25, 000 


12, 000 


Finished product sales 





Finished product holdover 


25, 000 







1 Milk received from milk marketing association: Monday, 5,000 gallons; Tuesday, 4,000 gallons; Friday, 8,000 
and Saturday, 4,000 gallons. The rest of the milk is received from local producers. 

2 Figures rounded to the nearest ten. 

3 The amount of finished products needed for Wednesday and Thursday distribution. 



gallons; 



35,000 gallons of milk weekly, and each item of 
equipment is numbered in a similar manner. 
Tanker-Receiving Shelter 

The suggested receiving shelter is 31% feet by 
69 feet. It should be of the same general design 
and construction as the receiving shelter Sug- 
gested for the plant handling 35,000 gallons a 
week. The equipment suggested consists of a re- 
ceiving pump with a capacity of 180 gallons per 
minute (2), an automatic CIP unit (32), and two 
CIP transport-tank washers on hoists (35). 
Raw-Milk Storage Room 

The raw-milk storage room is 22 feet wide and 
52 feet long. It contains 1,144 square feet of 
space. Three 7,000-gallon raw-milk storage 
tanks (4A, 4, and 5) are suggested for raw milk 
and standardized milk ready for pasteurization. 
A 4,000-gallon storage tank (6) is suggested for 
holding skim milk received from the separator- 
clarifier (9). 

The CIP features, refrigerated wall surfaces, 
and load cells of these tanks are the same as those 
discussed for the smaller plant. 

The raw-milk storage and standardizing tanks 
are connected to a 3-line sanitary header system 
(fig. 14). 

Processing and Filling Room 

The processing and filling room for the plant 
contains 4,581 square feet of space. An area 72% 
feet by 58^ feet, containing 4,256 square feet, 
provides space for the control panel, processing 
equipment, and filling and stacking equipment, 
An area 22 feet by 1434 feet, containing 325 square 
feet, provides space for the surge tanks, which are 
considered to be part of the processing equipment, 
The walls and floors of this room should be of the 
same, construction and the ceiling the same height 
as described for the smaller plant, 



The functions of the control panel are the same 
as those for the smaller plant, The panel is 
about 4 feet 7 inches high and 11 feet 5 inches 
long. 

The processing equipment perforins the same 
functions as those described for the plant han- 
dling 35,000 gallons of milk weekly. The basic 
difference between the equipment suggested for 
the two plants is that the equipment for this plant 
has a greater capacity. For example, milk is sep- 
arated in this plant at the rate of 11,000 pounds 
per hour and in the smaller plant at 5,500 pounds 
per hour. 

The processing equipment suggested consists of 
a separator-clarifier (9) that separates 11,000 
pounds per hour or clarifies 40,000 pounds per 
hour, a 1,000-gallon half-and-half vat (10), a bal- 
ance tank (12), a vitamin feed cabinet (13), plate 
heat exchanger with a capacity of 3,500 g.p.h. 
(14) , a positive displacement timing pump (15) , a 
holder tube (16), an ultra-high-temperature 
heater (17), a homogenizer with a capacity of 
3,500 g.p.h. (18), a surge tank holding 3,000 gal- 
lons of pasteurized milk (19), a surge tank hold- 
ing 1,000 gallons of half-and-half (20), a transfer 
pump with a capacity of 75 g.p.m. (7), a positive 
displacement pump with a capacity of 20 to 70 
g.p.m. (8), and a hot water heating and circulat- 
ing unit (50) for the HTST system. Items of 
equipment suggested for cleaning purposes are an 
automatic CIP unit (31), a CIP solution return 
pump (34), with a capacity of 160 g.p.m., and a 
COP portable wash tank (33). 

Two filling machines are suggested, one filling 
75 quart or pint cartons per minute (21) , and one 
filling 72 half-gallon cartons per minute (22). 
The arrangement of fillers, with their automatic 
casers (23) and automatic case stackers (24), 
above-floor case conveyor (30), and automatic case 

27 









111 I§ II * * 




28 



LOAD CELLS - 2 EACH TANK 




AUTOMATIC VALVES 



Figure 14. — Raw-milk storage tanks are equipped with automatic valves to control the flow of milk and load cells to 

weigh the milk in the tanks. 



divider (29), is similar to that suggested for the 
smaller plant. 

A recirculating washer (33) is suggested for the 
machinery and equipment that must be dismantled 
for cleaning. To utilize space efficiently, the 
washer is located behind the half-and-half vat 
(10). 

Cold Room and Docks for Retail Trucks 

As shown in table 2, the maximum holdover of 
finished milk products occurs on Tuesday and 
amounts to 35,000 gallons. Byproducts, amount- 
ing to 3,500 gallons, also must be stored. Thus, the 
cold room should provide space for storing 38,500 
gallons of milk, half-and-half, and byproducts. 
This would be the equivalent of 9,044 cases, based 
on packaging in the same ratio of container sizes 
and the same size case as assumed for the plant 
handling 35,000 gallons of milk weekly. 

If cases are stacked five high, floor space for 
1,809 stacks would be needed. At 1.36 square feet 
of floor space per stack, total floor space required 
for 1,809 stacks would be 2,460 square feet. 

If half the stacks were stored in the area for 



reserves of finished products, and 20 percent of 
the area was used for aisle and conveyor space, 
1,538 square feet would be needed for this area. 
The other half of the cases would be stored in the 
area where retail orders are assembled. If 50 
percent of this area was used for aisles and a con- 
veyor, and for making up orders, the area would 
require 2,460 square feet. Thus, the cold room 
space needed would amount to 3,998 square feet. 
The L-shaped room in the layout contains 4,092 
square feet of space. The short section of the L, 
26 feet by 57 3 /4 feet, is part of the building proper ; 
the long section, 28 feet by 921/2 feet, projects out 
from the building. 

Two sides of this section have nine sliding doors 
each; these doors are on 10-foot centers and are 
used for loading out retail route trucks. Trucks 
for four routes, averaging 50 cases each, could be 
loaded daily from each door. Thus, 3,600 cases 
for 72 retail routes could be loaded per day from 
the 18 doors. The remaining cases would be dis- 
tributed by a wholesale route and would be loaded 
from the in-floor conveyor (25) at the end of the 
cold room. 



29 



The construction of the cold room is similar to 
that described for the smaller plant. Refrigera- 
tion is provided by five direct expansion cooling 
units (53) suspended from the ceiling. 

The dock for loading retail and wholesale trucks 
and receiving empty cases should be of the same 
general design as that suggested for the plant 
handling 35,000 gallons of milk weekly. 

Storage Rooms 

As in the smaller plant, separate rooms are pro- 
vided for storing empty cases, paper containers, 
and miscellaneous dry supplies. 

The empty-case storage room contains auto- 
matic case unstacker ('27). case washer (28), sup- 
ply tank for conveyor lubricant (60), the in-floor 
conveyor (25), and stack feed magazine (26). 

The maximum number of empty cases to be 
stored would be approximately equal to the max- 
imum number stored in the cold room. Therefore, 
the room should provide space for 1.809 stacks. 
These stacks would require 2,460 square feet of 
space. Allowing 20 percent for the in-floor con- 
veyor and passageways, a total of 3,075 square 
feet would be needed. 

The equipment requires a space 10 by 30 feet, or 
300 square feet. This space, added to storage re- 
quirements, indicates that a minimum of 3,375 
square feet would be needed. A room 74% feet 
by 52!/2 feet, 3,011 square feet of space, is sug- 
gested. The room should be of the same general 
design and construction as that suggested for the 
empty-case storage room for the smaller plant. 

The criteria for determining the amount of 
space needed for the paper-container storage 
room are the same as those for the plant handling 
35,000 gallons of milk weekly. The storage re- 
quirements for this plant total 951,000 cartons (a 
2-week supply plus a truckload lot ) . This amounts 
to about 77 pallet loads. A room containing 1,567 
square feet of space is suggested. This size of room 
would allow sufficient space to rotate the inventory 
properly and would also provide ample space for 
an 8-foot aisle for moving containers into and 
out of the room with a walk-behind type of fork- 
lift truck. The construction of the empty con- 
tainer room should be the same as that suggested 
for the plant handling 35.000 gallons of milk 
weekly. 

A dry storage room 23% feet by 110 feet, con- 
taining 2,613 square feet of space, is suggested. 
This room would be used for the same purposes 
and should be of the same construction as that 
described for the smaller plant. 

Laboratory and Office Areas 

Separate rooms are suggested for the laboratory 
and the plant office because in all probability the 
workload in each room would require a full-time 
worker. The construction of these two rooms 
would be the same as that described for the 
smaller plant. 



The laboratory would house equipment for mak- 
ing butterfat and bacteriological analyses. The 
suggested room is 10 feet wide and 18 feet long. 

The plant office would house the superintendent's 
desk and provide space for plant records and for 
making out production schedules and reports. The 
suggested room is 8}/ 2 ^ ee t by 10 feet and contains 
85 square feet of space. 

The main office would provide space for a re- 
ception room, a vault, a general office, a manager's 
office, a sales manager's office, storage, a drivers' 
room, a locker room for drivers, and toilets. 

A lunchroom 15 feet by 21 feet is suggested for 
office and plant workers. 

The suggested toilet and locker room for plant 
workers is 15 feet by 2-1 feet and contains 360 
square feet of space. The locker room is 15 feet 
by 14 feet : it provides space for 15 workers. The 
construction of this room should be the same as 
that suggested for the smaller plant. 

Cleaned-in-Place Equipment Room 

An area to the rear of the raw-milk storage 
tanks is suggested for the automatic CIP unit (31) 
and for storing a small amount of cleaning com- 
pounds. A second automatic CIP unit (32) is 
located in the tanker-receiving shelter because it 
is principally used to clean transport tanks. 

Refrigeration Equipment Room 

The suggested refrigeration equipment room is 
35% feet by 49 feet and contains about 1.752 
square feet of space. The room has an outside 
doorway large enough to move ammonia compres- 
sors in or out and doorways to the boiler room 
and plant. 

Eef rigeration equipment in the room consists of 
two sweet-water pumps (41). a 46,000-pound ice 
builder (42), a 50-hp., 35-ton ammonia com- 
pressor (44) , a 30-hp., 27-ton ammonia compressor 
(45), and a 20-inch by 16-foot ammonia receiver 
(47). (See appendix.) A 65-ton ammonia 
evaporative condenser (48) is located outdoors 
adjacent to the wall near the ammonia receiver 
(47) so that the condensed liquid ammonia will 
drain back to the ammonia receiver by gravity. 

Other equipment in this room consists of a 20-hp. 
air compressor (52) and an electric distribution 
panel (51). 

Boiler Room 

The suggested boiler room is 35% feet by 24 
feet, containing 858 square feet of space. Two 
steam boilers each with 75 boiler-horsepower (36 
and 37). a system for feeding water to the boilers 
(38), and a hot water tank (40) are suggested for 
the room. (See appendix.) 

One of the boilers would handle the hot water 
heating, pasteurizing, and incidental requirements 
for the plant during mild weather; the second 
boiler would serve as a standby and would be 
used for short periods when the weather was 
extremelv cold. 



30 



Provision for Plant Expansion 

The layout of this plant provides for a future 
expansion to 210,000 gallons. Part of the expan- 
sion would necessitate changes in the physical 
plant and part would require equipment changes. 
The components of the plant which would require 
more area are the cold room, the empty-case 
storage room, the dry storage room, the paper- 
container storage room, and the main office. A 
total of 13,090 square feet is suggested. Thus, the 
present plant could double its capacity with the 
addition of only 41 percent more usable floor 
space. 

Expansion of the cold room would necessitate 
the removal of one exterior wall. An area 36 
feet by 140 feet, containing 5,040 square feet 
would be added. An area 24^ feet by 741/4 feet, 
containing 1,819 square feet, would be added to the 
empty-case room. This addition would come 
from a part of the present dry storage room. An 
area 24% feet by 34% feet, containing 851 square 
feet of space, would be added to the paper-con- 
tainer storage room. This addition also would 
come from a part of the present dry storage room. 

A new dry storage room 50 feet by 111 feet 
would be added to the building. The main office 
would be enlarged by 1,600 square feet, by addi- 
tion of an area 40 feet by 40 feet. More frequent 
deliveries of supplies would reduce the space re- 
quirements for the dry storage and the container 
storage rooms. 

The tanker-receiving shelter would be inade- 
quate to handle 210,000 gallons of milk weekly 
if all the milk were received on one workshift. 
For future expansion, it is suggested that two 
workshifts be utilized for receiving. Raw-milk 
storage facilities would be expanded by adding 
a 10,000-gallon storage tank (3). 

Expansion in the processing and filling room 
could be made by using the separator-clarifier (9) 
as a separator only and operating it for a longer 
period; adding two clarifiers with a capacity of 
40,000 pounds of milk per hour each (62) ; re- 
placing the 1,000-gallon surge tank (20) with a 
6,000-gallon surge tank (19A) ; expanding the 
plate heat exchanger (14) to handle 7,000 gallons 
per hour; replacing the homogenizer, capacity 
3,500 gallons per hour (18), with one with a ca- 
pacity of 7,000 gallons per hour; installing two 
additional carton fillers — one filling 72 half- 
gallon cartons per minute (58) and one filling 75 
quart or pint cartons per minute (59) ; installing 
two machines each packing 100 cartons in cases 
per minute (63) ; installing two automatic stack- 
ers that will stack 15 cases per minute each (64) ; 
and installing a vat holding 1,000 gallons of half- 
and-half (11). The addition of this equipment 
would permit doubling the processing rate to 
7,000 gallons of milk per hour. 

In the empty-case storage room, the case un- 
stacker would have to be modified and the case 
washer would have to be replaced to handle the 



additional cases needed for the added fillers. The 
automatic case unstacker (27) would be speeded 
up from 15 cases per minute to 26 cases per min- 
ute and the machine that washed 15 cases per 
minute (28) would be replaced by one washing 
30 cases per minute (65). The stack feed maga- 
zine (26) would be adequate to handle the in- 
creased number of empty cases. 

No expansion would be required in the labora- 
tory, plant offices, locker or toilet rooms, the 
lunchroom, or the boiler room. 

To expand the refrigeration system to handle 
210,000 gallons of milk, another ammonia com- 
pressor (46) would be needed. Provisions are 
made in the present room for it. In addition, 
an evaporative condenser (49) and an ice builder 
(43) would be needed. This equipment would be 
located just outside the building. 

Plant Site 

The principles determining the type of site 
needed for a plant handling 105,000 gallons of 
milk weekly are the same as those for the plant 
handling 35,000 gallons weekly. 

The plot plan for the suggested plant is shown 
in figure 15. The plant is located on a site 690 
feet wide and 433 feet deep, which contains about 
6.9 acres. The plant proper contains 32,318 square 
feet and is located to one side and toward the front 
of the site. It is suggested that the areas directly 
in front and adjacent to the main office building, 
and along the front of the site, comprising about 
24,000 square feet, be landscaped. 

Three paved driveways, 30 feet wide, would con- 
nect the plant with the highway. Two of the 
driveways, one on each side of the site, would be 
used primarily by truckers. Aprons connecting 
with the major docks of the plant should be not 
less than 70 feet wide and should have a paved sur- 
face. A driveway at the center of the site would 
be used primarily by passenger cars. 

Well-defined parking areas should be provided 
on the site for 160 motor vehicles. These areas 
should be out of the traffic lanes, but easily access- 
ible from them. The parking spaces should be 
paved and well drained. Individual spaces for 
88 automobiles should be ll 1 /? feet wide and 20 
feet deep, and for 72 trucks, 12^ feet wide and 25 
feet deep. All truck spaces should be equipped 
with electric plug-in lines. A gas island should 
be located to the rear of the site near the garage. 

Schedule of Equipment Use 

The schedule for use of equipment for the peak 
processing day of the week is shown in figure 16. 
On the peak day 21,600 gallons of market milk 
and 900 gallons of half-and-half would be proc- 
essed. The time periods for cleaning various 
equipment are also shown in figure 16. 

A diagram illustrating product flow is shown in 
figure 17. 



31 




f ^ 



32 



EQUIPMENT H0UR 0F ° AY 

6A.M 789 10 II 12 1234567 8PM 




































TANK (4) ±_ 


J 


E| K 


Q 


A 1 


\ 


I 










j n~\ 








—\ 


TANK(4A) \_ 


J | B 1 J |E| K 


H ] Q | A 


E| K 


TANK (5) 

TANK (6) 

VAT (10) 

SEPARATOR-CLARIFIER (9) 

PUMP (7) 

PUMP (8) 

HTST SYSTEM (12 THRU 18) 

SURGE TANK (19) 

SURGE TANK (20) 

1/2 GALLON FILLER (22) 

QUART-PINT FILLER (21) 

CLEAN SANITARY LINES 




1 1 




1 








A 


J|E| K ! 


o 1 




E,L£ 


E F 




f 


Q 1 






c in i nui 




1 1 1 


D | !Vi JF| 


Q 




Si 


1 1 1 


1 




B 1 


G 


Q 








V\ 






\ 








\L 


Q 




C" B 


G 


' 








1 1 1 1 1 


H III 


1 Q 1 


1 1 1 1 I 






K| o ! 


1 o 1 


















|N| P | 


1 Q 1 










LZ 


Q 


: 


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Ri ! 






LEGEND 

A RECEIVE 3.8% MILK. J. HOLD 3.8% MILK. 

B. SEPARATE 3.8% MILK. K. HOLD 3.5% MILK. 

C. SEPARATED 0.1% SKIM. L. HOLD 0.1% SKIM. 

D. SEPARATED 15% FAT PRODUCT. M. HOLD 15% FAT PRODUCT. 

E. STANDARDIZE 3.8% MILK N. HOLD 11% HALF 8 HALF. 
TO 3.5% MILK. 0. FILL 3.5% MILK. 

F. STANDARDIZE 15% FAT PRODUCT P. FILL 11% HALF 8 HALF. 
TO 11% HALF 8 HALF. Q. CLEAN EQUIPMENT. 

G CLARIFY 3 5% MILK. R RAW LINES. 

H PROCESS 3 5% MILK. S. PASTEURIZED LINES. 

I PROCESS 11% HALF 8 HALF. 



Figure 16. 



-Schedule of assumed use of equipment for a peak processing day (22,500 gallons) for a special-purpose 
plant handling 105,000 gallons of milk weekly. 



About 2,650 gallons of milk with a butterfat 
content of 3.8 percent, held over from the previous 
clay, would be separated. Tank (4) would provide 
the milk for separation. Separation would begin 
about 6 :45 a.m. and end about 8 :50 a.m. The 
skim milk would be diverted to tank (6) and the 
15-percent fat product to vat (10) . 

Receiving would begin about 7 a.m. and con- 
tinue intermittently until about 3 :15 p.m. About 



6,400 gallons of raw milk would be received in 
tank (5), 6,500 gallons in tank (4), and 4,100 in 
tank (4A). The total amount received is 17,000 
gallons. Pump (2) would be used for transfer- 
ring raw milk from truck tanks to storage tanks. 
About 6,500 gallons of the milk would be held over 
in tank (4) for the next day's operations. 

Raw milk with a butterfat content of 3.8 per- 
cent would be standardized to 3.5-percent butter- 

33 



TANK 
TRUCK 



D 



/FUTURE \ r 

I 10,000 i ' 

^storage/ 

RECEIVE & STANDARDIZE ■*■ 
TO HTST 



SKIM TRANSFER 




QT PINT 
FILLER 



1/2 GAL. 

[FILLER 

22 



LEGEND 

-<j>- ^ 3 WAY LINE OR MANIFOLD VALVE 
-o- 2 WAY OUTLET OR STOP VALVE 

>|hd 2 WAY THROTTLING VALVE 

b- CENTRIFUGAL PUMP 

POSITIVE DISPLACEMENT PUMP 



Figure 17. — The product flow from tank trucks to filling machines. 



34 



fat by pumping skim milk from tank (6) to tanks 
(4, 4A, and 5). Milk in tank (4) would be stand- 
ardized between 9 a.m. and 9:20 a.m. Milk in 
tank (4A) would be standardized between 9:20 
a.m. and 9 :35 a.m., and later receipts in this tank 
would be standardized between 1 :00 and 1 :15 
p.m. Milk in tank (5) would be standardized be- 
tween 10 :10 a.m. and 10 :30 a.m. 

Half-and-half would be standardized in vat 
(10) between 10:35 a.m. and 10:50 a.m. and held 
in the vat until it is processed at 4 :10 p.m. Pump 
(7) would transfer skim milk from tank (6) to 
vat (10). 

Processing market milk would begin about 
10 a.m. and continue until 4:10 p.m. Tank (4A) 
would supply raw standardized milk for process- 
ing at two different times — 10 a.m. to 10 :55 a. m., 
and 2:55 p.m. to 4:10 p.m.— tank (4) from 10:55 
a.m. to 12:55 p.m., and tank (5) from 12:55 p.m. 
to 2:55 p.m. The flow of market milk during 
pasteurization and homogenization is similar to 
that described for the small plant. 

Half-and-half would be processed between 4 :10 
p.m. and 4:25 p.m. 

After pasteurization and homogenization begin 
at 10 a.m., processed market milk begins to ac- 
cumulate in surge tank (19). The half-gallon 
filling machine (22) would start at 10:20 a.m. 
and the quart-pint filler at 10 :45 a.m. The elapsed 
time for filling for market milk is 7 hours. 

Half-and-half would be put into cartons from 
4 :45 p.m. to 6 :20 p.m. 

How the Plant Operates 

Plant operations are similar to those of the 
plant handling 35,000 gallons per week, except for 
the CIP system. 

The suggested control panel for the plant is 
shown in figure 18. 

Automatic CIP unit (31) is used for cleaning 
raw-milk storage tanks (4, 4A, 5, and 6), half- 
and-half vat (10), and pasteurized milk surge 
tanks (19, 20). The equipment to be cleaned is 
selected on the CIP Selector switch. The oper- 
ations to be performed are selected on the Master 
selector; for example, "Clean," "Clean and san- 
itize," or "Sanitize only." 

Automatic CIP unit (32) is used for cleaning 
tank trucks, raw milk lines, HTST system, and 
pasteurized milk lines. This unit has its own "Se- 
lector" and "Master selector" switches. 

Selection of any cleaning job provides the auto- 
matic makeup of the cleaning solutions, circula- 
tion of the solution through the equipment for a 
predetermined time, and proper valve sequencing' 
to insure that all lines and valves are cleaned. 

CIP unit (32) also has a "Selector" and "Master 
selector" switch in the tanker-receiving shelter for 
the worker receiving the milk to use. This switch 
eliminates the need for frequent trips to the con- 
trol panel (1) when milk is received. 



Labor Requirements 

Eleven workers other than the office crew and 
route truck drivers would be required to operate 
the automated plant handling 105,000 gallons of 
milk weekly. This is six fewer workers than 
would be required in a typical nonautomated 
plant handling a similar volume. As with the 
automated plant handling 35,000 gallons of milk 
weekly, the reduction is due to the use of labor- 
saving equipment, which requires fewer workers 
or permits workers to perform additional duties. 

The crew for the automated plant would consist 
of a supervisor, a relief man, two maintenance 
workers (who would also operate the heating and 
refrigeration systems), a laboratory technician, 
and six other workers. These six workers perform 
all the basic operations required in the receiving, 
processing, packaging, and storing of milk and 
the receiving and handling of empty cases and 
containers. The crew for a nonautomated plant 
would consist of 17 workers : A supervisor, 2 re- 
lief workers, a maintenance worker, a laboratory 
technician, and 12 other workers to perform the 
basic operations. 

A relief worker is used to fill in for absentees, 
relieve other workers for rest periods, and fill in 
for workers on vacation. Two relief workers are 
required in a nonautomated plant because more 
relief work is necessary. In an automated plant 
only one relief worker would be required because 
there are fewer workers to be relieved, and some 
workers would be able to arrange rest or lunch 
periods to correspond with the time the machines 
require no attention. An illustration is the auto- 
mated cleaning of raw-milk storage tanks or tank 
trucks. 

Two workers would be required for maintenance 
work and to operate the refrigeration and heating 
systems in the automated plant ; one worker would 
be needed in a nonautomated plant. The mainte- 
nance work would be greater in the automated 
plant. 

Two workers would be required for receiving 
the raw milk and standardizing, separating, and 
pasteurizing it in the automated plant, compared 
with four workers in the nonautomated plant. 
This reduction is due almost solely to automation. 

One worker would be required for the packag- 
ing, casing, and stacking operations in the auto- 
mated plant, and four workers would be needed 
in the nonautomated plant. Automatic fillers, 
casers, and stackers are responsible for this 
reduction. 

Two workers would be required by both the 
automated and nonautomated plant to perform 
the cold room work and to make up orders. 

One worker would be required to perform the 
work in the empty-case storage room, dry storage 
room, and paper-container storage room in the 
automated plant, compared with two workers in 
the nonautomated plant. This reduction is made 



35 











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It 

s s-e-g : 1°: : 




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11) <@{| II (®3 



36 



possible by the use of the stack feed magazine, 
automatic case unstacker, and an automatic case 
divider. 

Thirteen workers devote part of their time to 
cleaning equipment in the nonautomated plant, 
compared with eight workers in the automated 
plant. Furthermore, the eight workers devote 
considerably less time to cleaning. The automatic 
cleaned-in-place system makes this reduction in 
labor possible. 

Costs and Possible Benefits of Labor- 
Saving Equipment 

The equipment required for the automated plant- 
to reduce the labor requirements would consist of 
a control panel (1), remotely controlled sanitary 
valves, load cells, automatic casers (23) , automatic 



case stackers (24), stack feed magazine (26), au- 
tomatic case unstacker (27), automatic case di- 
vider (29), and automatic CIP units (31 and 32). 
The estimated cost of this additional equipment 
would be $110,000. 

It is estimated that the automated special- 
purpose milk plant handling 105,000 gallons 
weekly could operate with at least six fewer work- 
ers than would be required for a nonautomated 
plant handling the same volume. Based on an 
assumed cost of $6,500 annually per worker (sal- 
ary plus fringe benefits) , the annual savings would 
amount to $39,000. If 20 percent of the cost of the 
equipment is allowed annually for owning and op- 
erating the equipment (depreciation, maintenance, 
interest, insurance, and taxes), the cost would be 
$22,000, and an annual saving of $17,000 would 
result. The saving should amortize the cost of the 
equipment in about 6V2 years. 



Appendix: Refrigeration, Heating, and Ventilating Systems 



Production per man-hour of labor should be 
higher in the automated plant. It is estimated 
that on a peak production day (22,500 gallons) 
the production in the automated plant would be 
256 gallons of milk per man-hour, compared with 
165.3 gallons in the nonautomated plant. Based 
on a weekly production of 105,000 gallons of milk, 
the production per man-hour for the automated 
plant would be 239 gallons and for the nonauto- 
mated plant 154.3 gallons per man-hour. 
Roughly, the production per man-hour is 55 
percent greater for an automated special-purpose 
milk plant handling 105,000 gallons of milk 
weekly than for a nonautomated plant. 

Machine-controlled operations should reduce 
the in-plant losses of milk and provide more uni- 
form quality than is obtained in a nonautomated 
plant using conventional equipment. 

Plant Handling 35,000 Gallons of Milk 
Weekly 

Refrigeration System 

The refrigeration system for the suggested 
plant must be adequate to cool milk when neces- 
sary and to maintain the stored products at the 
required temperature in the cold room. Since am- 
monia is the refrigerant used in many dairy plants, 
this plant is set up for ammonia. 

Milk is cooled by circulating sweet water from 
the ice builder through insulated jackets in the 
tanks, vats, and plate heat exchanger. The ice 
builder is a refrigerant evaporator coil immersed 
in a tank of water. A reserve of ice is built up 
during slack periods to provide adequate refrig- 
eration when needed. Water enters the tank 
warm, circulates around the ice-covered coils, and 
is cold when it leaves the tank. 



The cold room is refrigerated by two direct 
expansion cooling units. Each unit has coils 
through which ammonia circulates, cooling them. 
Air is blown over these coils by a fan in the unit 
to cool the room. The refrigeration data herein 
are based partly on information in "Refrigeration 
Engineering Application Data," April 1940 2 , and 
partly on information in "Air Conditioning Re- 
frigeration Data Book," 1956-7 3 . 

The factors used in determining the sizes of 
equipment suggested for the plant are described 
in the following sections. The refrigeration re- 
quirements presented herein are offered as a guide 
only, since many factors could affect the calcula- 
tion for a particular plant. 

Milk Cooling Requirements 

On a peak day, 7,500 gallons of products would 
be cooled from 66° to 38° F. at the plate heat ex- 
changer, 300 gallons of half-and-half from 45° 
to 40° in the 400-gallon vat, and 4,000 gallons of 
milk from 45° to 40° in the raw-milk storage 
tanks. A 5-degree rise in temperature of the half- 
and-half in vat (10) and the raw milk in the 
storage tanks is assumed during the day. 

The cooling load (pounds of ice) may be com- 
puted by the formula that follows. For calcula- 
tion purposes, the latent heat of fusion of ice is 
144 B.t.u. per pound and the w T eight of milk and 
11-percent half-and-half is 8.6 pounds per gallon. 
The specific heat of milk is 0.94, but the figure 
used by industry, 1.0, is used herein to determine 
the cooling load. 



"American Society of Refrigerating Engineers. Air 
Conditioning Refrigerating Data Book. Applications 
Vol. 6th eel., illus. New York. 1956-7. 

3 Segal, S. Charles. Refrigeration Load Calculations — 
II. Temperatures Below 32° F. — Refrig. Engin. Applic. 
Data 12. Refrig. Engin. Vol. 39. No. 4, Sec. 2. April 1940. 



37 



volume v weight v specific heat ^temperature 
Cooling requirements _ o^milk X of milk x of mill change 



(pounds of ice) 

TVhen calculated by the above formula, the total 
daily refrigeration requirement for cooling milk 
in this plant is 13,825 pounds of ice. An addi- 
tional 10 percent is suggested to take care of losses 
from radiation, agitation, and pumping. There- 
fore, milk cooling : requires 15,208 pounds of ice. 
A 16,000-pound ice builder is suggested. 

Ice for cooling milk would be built up in the 



latent heat of fusion of ice 

ice builder in the 16 hours during the day when 
the processing room is not in operation to reduce 
the peak electrical load of the plant. The com- 
pressor capacity required for the ice builder is 
obtained by the' use of the following formula. In 
the formula, one ton of refrigeration is equal to 
288,000 B.t.u. per 24 hours. On an hourly basis 
this amounts to 12,000 B.t.u. 



Compressor capacity _ amount of ice required X latent heat of fusion of ice 
(tons) ~~12,000 (B.t.u. per hour)Xlength of operating period 



The compressor capacity required for building 
ice in the ice builder for cooling milk is 11.4 tons. 
A 12-ton ammonia compressor with a 15-horse- 
power motor is suggested. 
Cold Room Requirements 

The factors which determine the refrigeration 
requirements of the cold room are heat gain (A) 
through walls, ceiling, and floor, (B) through air 
changes in the cold room, (C) from milk cases, 
(D) from electrical energy, and (E) from milk 
coming into the room. A heat gain also is in- 
curred from workers storing and loading out stacks 
of cases in the room. However, for one worker 
performing all cold room operations in the pro- 
posed plant, the heat gain would be comparatively 
small and would be included in the suggested 
safety factor for the room. The refrigeration re- 



quirements for a cold room should be based on the 
peak average hourly load. For this analysis it is 
assumed that the cold room refrigeration load 
would be handled in 16 hours, and 8 hours would be 
allowed for defrosting cooler coils and for com- 
pressor downtime. 

Heat gains through walls, ceiling, and floor are 
calculated by the formula shown below. The cal- 
culations are based on a cold room temperature of 
35° F. and an outside temperature of 95°. An 
average overall coefficient of heat transmission for 
the walls, floor, and ceiling of 0.0756 B.t.u. per 
hour per square foot per degree F. temperature 
difference is suggested. This coefficient is equiv- 
alent to the heat transmission through a wall con- 
sisting of 8 inches of brick and 1 inches of insula- 
tion. The cold room is 30 by 50 feet (outside di- 
mensions), and the ceiling is 10 feet high. 



surface area, 
(square feet) 



Heat gain through walls, 
floor, and ceiling 
(B.t.u. per hour) 



The peak average hourly load from heat gain 
through walls, ceiling, and floors is 31,298 B.t.u. 

Heat gain through air changes is calculated by 
the following formula. The outside and inside 
temperatures for the room are the same as those 



0.0756 (B.t.u. 
per square foot) 



temperature 
change 



X24 



16 



j)reviously stated. Ten air changes per 24 hours 
are assumed for the room. The heat loss factor 
used is 2.53 B.t.u. per cubic foot per 24 hours for a 
temperature change of 60° F. The room contains 
15,000 cubic feet. 



i p 2.53 (B.t.u. per number of air 

„ t ■ 4 . . V0U T° Txcubic foot per X changes per 

Heat gam through (cubic feet) 2 4 hours) 24 hours 

infiltration = 

(B.t.u. per hour) 



16 



The peak average hourly load from heat gain 
from air changes is 23,720 B.t.u. 

Heat gain from milk cases is calculated by the 
formula that follows. For the purpose of this re- 
port, the milk cases used are assumed to be made 



of steel wire and each weighs 8 pounds. They 
would have a specific heat of 0.2 and enter the room 
at a temperature of 95° F. The number of cases 
entering the cold room on the peak processing day 
is 1,746. Boom temperature would be 35°. 



Heat gain from 

milk cases 
(B.t.u. per hour) 



Total number of weight specific i. nvn ~ nwi i„ 9n 
cases entering X of Xheat of x tem P erature 
room case case 

16 



chain 



38 



The peak average hourly load from heat gain 
from milk cases entering the cold room amounts to 
10, 476 B.t.u. 

Heat gain from electrical energy is based on the 
use of a 3-hp. motor for a conveyor operating 8 
hours, two ^-hp. blower motors operating 24 



hours, and 600 watts of electricity for lights for 
10 hours. 

Heat gain from electrical energy used for motors 
for the conveyor and blowers is calculated by the 
following formula. For the calculation, one horse- 
power-hour equals 3,700 B.t.u. per hour. 



Heat gain from motors 
(B.t.u. per hour) 



horsepower X 3,700 



The peak average hourly load from heat gain 
from motors is 14,800 B.t.u. 
The heat gain from electrical energy used for 



the lights is calculated by the following formula. 
For the calculation, one watt-hour equals 3.42 
B.t.u. per hour. 



Heat gain from lights_number of 



(B.t.u. per hour' 



watts 



X3.42 



The peak average hourly load from heat gain 
from lights is 2,052 B.t.u. 

The total peak average hourly load from heat 
gain from electrical energy is 16,852 B.t.u. 

Heat gain from milk entering the cold room is 
based on 7,500 gallons of milk (64,500 pounds), a 
cold room temperature of 35° F., and milk enter- 



ing the room at 40°. The specific heat of milk is 
0.94, but for these calculations 1 is used. The as- 
sumed temperature of the milk entering the room 
allows for a 2-clegree rise in temperature of milk 
from the time it leaves the plate heat exchanger. 
The heat gain from milk entering the cold room 
is calculated by the following formula : 



Pounds of milk v specific v temperature 



Product load 
(B.t.u. per hour) 



entering room r^ heat 
To" 



X 



change 



The peak average hourly load from products 
stored in the cold room amounts to 20,156 B.t.u. 

Total refrigeration requirements of the cold 
room are 112,752 B.t.u. This total includes the 
peak average hourly load for heat gain (102,502 
B.t.u.) plus a 10-percent safety factor (10,250 
B.t.u.) to allow for the many possible variations 



that enter into the calculations of refrigeration 
needs. 

The compressor capacity for the cold room 
would be determined by the use of the following 
formula. A ton of refrigeration is equal to 
288,000 B.t.u. per 24 hours, or 12,000 B.t.u. per 
hour. 



Refrigeration requirements = 
(tons) 



peak average hourly load 
12,000 



The total refrigeration needed for the cold room 
is 9.39 tons. Thus, a 10-ton-capacity ammonia 
compressor with a 15-hp. motor is suggested for the 
plant. Two cooling units are proposed for the 
cold room, and each unit would require a minimum 
of 4.69 tons of refrigeration. Each unit should 
have a capacity of 5 tons of refrigeration at a 
10-degree F. temperature difference between the 
refrigerant and the air being cooled. 

System Needed for the Plant 

In addition to the sweet- water pumps (41), ice 
builder (42), ammonia compressors (44 and 45), 
ammonia receiver (47), and evaporative condenser 
(48), two 5-ton cooling units are needed for the 
refrigeration system of the proposed plant. 

The cooling units would operate at a suction 
pressure of 39 pounds per square inch (p.s.i.) and 



a refrigerant temperature of 25° F. and the ice 
builder at 28 p.s.i. (refrigerant temperature 15°). 
The compressors would operate from a common 
suction line. 

A diagram of the suggested refrigeration system 
is shown in figure 19. 

Operation of the System 

Two automatic control devices are used in the 
refrigeration system— an ice thickness control and 
a thermostat. 

The ice thickness control automatically shuts 
off the compressor (44) when the ice on the coils of 
the ice builder (42) reaches a thickness equivalent 
to 16,000 pounds. This amount of ice closes sole- 
noid valves (S3) and (S4). Closing valve (S3) 
shuts off the supply of ammonia to the ice builder. 
Closing valve (S4) diverts the ammonia suction 



39 



1 

CM 


_JL._ 


1 ? 


7 




s 




10 





53 
COOLING UNITS 



BPfiZ 



«4 



AMMONIA COMPRESSORS 950 F 



EVAPORATIVE 
CONDENSER 



AMMONIA RECEIVER 



LEGEND 

S SOLENOC VALVE 
BPR BACK PRESSURE REGULATING VALVE 
X THERMAL EXPANSION VALVE 



Figure 19. — A refrigeration system for an automated special-purpose milk plant handling 35,000 gallons of milk weekly. 



through the back pressure valve (BPR) set at 
30° F. which helps hold ice on the coils. 

The ice builder could be started automatically, 
but it is believed desirable to have this operation 
manual. The switch to start the ice builder would 
be located in the refrigeration room. 

The thermostat in the cold room automatically 
starts the compressor (45) when the temperature 
of the cold room rises to 38° F. When the com- 
pressor starts, solenoid valve (S2) opens and 
liquid ammonia flows to the cooling coils. When 
the temperature of the room reaches 35°, the ther- 
mostat stops the compressor, solenoid valve (S2) 
closes, and the supply of ammonia to the coils is 
cut off. 

At night when compressor (45) is off and com- 
pressor (44) is building up ice in the ice builder, 
compressor (44) will pump the supply of ammonia 
from the cooling coils. When the temperature of 
the coils rises above freezing, fans melt the ice on 
the coils. 

Refrigeration of the raw-milk storage tanks and 
the half-and-half vat is controlled by pushbuttons 
in the control panel. When a pushbutton is de- 
pressed, a solenoid valve (S) opens, and pump 

40 



(41) starts circulating sweet water to the equip- 
ment selected. 

Heating System 

The heating system provides hot water and steam 
for heating milk products, for cleaning, and for 
heating the building. The heating requirements 
may be fairly constant for a given amount of 
milk and milk products, but the requirements for 
cleaning and for heating the plant may vary 
widely. A major factor contributing to this vari- 
ation would be the plant's location. 

The capacity of the HTST pasteurizer is 12,000 
pounds per hour (1,400 g.p.h.) . Milk is heated in 
the plate heat exchanger by regeneration from 
40° F. to 144°, and by hot water from 144° to 
170°. It is heated by a direct infusion of steam in 
the ultra-high-temperature heater from 170° to 
210°. The total heating range by hot water and 
steam is 66°. 

In calculating the requirements for heating milk 
and milk products for the plant, one boiler horse- 
power is considered equivalent to the heat re- 
quired to evaporate 34.5 pounds of water in one 
hour. This is equivalent to a heat output of 



33,524 B.t.u. per hour. Common practice is to use 
35,000 B.t.u. per hour instead of 33,524 when con- 
verting to boiler horsepower. 



The energy requirements for pasteurizing milk 
and milk products may be calculated by the fol- 
lowing formula : 



Heat 
(B.t.u. per hour) 



P °Z"\°on^ ilk X te Xr Specific heat 



The energy requirements are 792,000 B.t.u. 
Dividing this figure by 35,000 for converting to 
boiler horsepower gives 22.6. A 50-boiler-horse- 
power automatic steam boiler (36) is suggested, 
however, to provide the additional steam and hot 
water needed for cleaning and plant heating. 

The tanker-receiving shelter and the refriger- 
ation room would be heated by unit heaters (57) 
suspended from the ceiling. The heaters are con- 
trolled by thermostats. The boiler room would re- 
quire no heat other than that radiated from the 
boiler. The processing and filling room, empty- 
case storage room, dry storage room, paper-con- 
tainer storage room, laboratory, locker and toilets 
would be heated by ducts from an air circulation 
and heating unit (55) mounted on the roof above 
the empty-case storage room. 



change 

The general office would be heated by ducts 
from another air circulation and heating unit (56) 
mounted on the roof above the office. 

Ventilation and Air Conditioning 

The tanker- receiving shelter, the refrigeration 
room, and the boiler room could be ventilated by 
window fans. 

The processing and filling room, the empty-case 
storage room, dry storage room, paper-container 
storage room, laboratory, and locker and toilet 
room would be ventilated by ducts from the air 
circulation and heating unit (55) mounted on the 
roof above the empty-case storage room (fig. 20). 
This unit would circulate 20,000 cubic feet of air 
per minute (c.f.m.) . 




E 




FRESH AIR INLET 



RE< IRCULATED AIR INLET 



Figure 20. — A roof-type air circulating and heating unit that will circulate 20,000 cubic feet of air per minute. 



41 



Beccause of high humidity, the processing and 
filling room would have one complete air change 
every 3 minutes: other areas would have air 
changes every 7 minutes. The slight positive air 
pressure in the plant would reduce the entry of 
nonfiltered air through doors and windows. 

The office area would be ventilated by an air con- 
ditioning unit (56) mounted on the roof. This 
unit would circulate 5,000 cubic feet of air per min- 
ute and would be similar to the one used for the 
plant. 

Both units would employ two-speed fans. Slow 
speed is used for winter heating and high speed for 
summer ventilation or air cooling. 

Plant Handling 105,000 Gallons of Milk 
Weekly 

Refrigeration System 

The refrigeration system for this plant is the 
same as that suggested for the smaller plant. 
However, the system for the plant handling 105,- 
000 gallons of milk per week naturally would be 
larger. 

Milk Cooling Requirements 

The milk cooling load would consist of cooling 
22,500 gallons of products at the plate heat ex- 
changer (the peak day's volume) from 66° to 38° 
F., 900 gallons of half-and-half in the 1,000-gallon 
vat from 45° to 40°, and 12,000 gallons of milk in 
the raw-milk storage tanks from -±5° to 40°. A 
5-degree rise in temperature of half-and-half and 
raw milk during the day is assumed. 

The total refrigeration requirements for cool- 
ing milk, based on the formula used for the plant 
handling 35,000 gallons per week, are 41,177 
pounds of ice. Allowing 10 percent for heat 
gained from radiation, agitation, and pumping, 
the total refrigeration requirements amount to 
45,625 pounds of ice. A -46,000-pound ice builder 
is suggested. 

The compressor capacity required for the ice 
builder, based on the same formula used for deter- 
mining the compressor capacity for the smaller 
plant, is 34.5 tons. Therefore, a 35-ton-capacity 
ammonia compressor with a 50-hp. motor is sug- 
gested for the ice builder. 

Cold Room Requirements 

The factors that determine the refrigeration re- 
quirements of the cold room are the same as those 
listed for the smaller plant. However, the require- 
ments would be different because the room is larger 
and the volume handled is greater. The require- 
ments would be determined for the individual fac- 
tors by the same formulas as those given for the 
smaller plant. The refrigeration and defrosting 
cycles also would be the same. 

The heat gain through walls, ceiling, and floor 
for the cold room is based on 12,480 square feet 
of surface area, a cold room temperature of 35° 



F. and an outside temperature of 95°, and a co- 
efficient of heat transmission of 0.0756 B.t.u. per 
square foot per degree F. temperature difference. 
The peak average hourly load amounts to 84.913 
B.t.u. 

The heat gain through air changes is based on 
41,120 cubic feet of space, a heat loss factor of 2.53 
B.t.u. per cubic foot per 24 hours for a tempera- 
ture change of 60° F., and 10 air changes per 24 
hours. The peak average hourly load amounts to 
65,021 B.t.u. 

The heat gain from milk cases is based on 5,237 
cases entering the room in 24 hours (an average 
hourly rate of 218.21 cases), a weight of 8 pounds 
per case, cases having a specific heat of 0.2, and a 
temperature difference of 60° F. The peak aver- 
age hourly load amounts to 31,423 B.t.u. 

The heat input from electrical energy is based 
on motors having 10y 2 hp. and 1,800 watts in elec- 
tric lights. One horsepower-hour equals 3,700 
B.t.u. per hour, and one watt per hour equals 3.42 
B.t.u. per hour. The peak average hourly load 
amounts to 45,006 B.t.u. 

The heat gain from milk entering the cold room 
is based on 22,500 gallons or 193,500 pounds (the 
peak day's volume) of milk with a specific heat of 
1, and a 5-degree F. temperature change. The 
peak average hourly load amounts to 60,469 B.t.u. 

Total refrigeration requirements of the cold 
room are 315,515 B.t.u. This total includes the 
peak average hourly load for heat gain (286,832 
B.t.u.) plus a 10-percent safety factor (28,683 
B.t.u.). 

The refrigeration system needed for the cold 
room would be calculated by the formula used for 
the smaller plant. The total number of tons of 
refrigeration needed for the cold room is 26.3. 
Thus, a 27-ton-capacity ammonia compressor with 
a 30-hp. motor is suggested. Five cooling units 
are proposed for the cold room, and each unit 
would require a minimum of 5.26 tons of refrig- 
eration. Each unit should have a capacity for 6 
tons of refrigeration at a 10-degree F. temperature 
difference between the refrigerant and the air 
being cooled. 

System Needed for the Plant 

The refrigeration system suggested for the 
plant, based on the requirements shown herein, 
would consist of the equipment listed under "Re- 
frigeration Equipment Boom" (page 30) and five 
6-ton cooling units in the cold room. 

The five cooling units would operate at a suction 
pressure of 39 p.s.i. at a refrigerant temperature 
of 25° F., and the ice builder at a suction pressure 
of 28 p.s.i. at a refrigerant temperature of 15°. 
The compressors would operate from a common 
suction line. 

A diagram of the suggested refrigeration sys- 
tem is shown in figure 21. The operation of the 
system would be similar to that described for the 
smaller plant. 



42 



AMMONIA RECEIVER 




LEGEND 

S SOLENOID VALVE 
BPR BACK PRESSURE REGULATING VftLVE 
X THERMAL EXPANSION VALVE 



Figure 21. — A refrigeration system for an automated milk plant handling 105,000 gallons of milk weekly. 



Heating System 

The heating system suggested for this plant 
would be similar to but larger than the one sug- 
gested for the plant handling 35,000 gallons of 
milk weekly. 

The pasteurizing capacity of the plant is 30,100 
pounds per hour (3,500 gallons per hour). The 
heating range is 66° F. 

Based on the same formulas used for calculating 
the boiler-horsepower requirements for heating 
milk and milk products for the plant handling 
35,000 gallons of milk weekly, the requirements 
for this plant are 56.8. 

Two automatic steam boilers of 75 boiler-horse- 
power each (36) and (37) are suggested for heat- 
ing milk and milk products, for cleaning, and for 



heating the plant. One would be adequate during 
mild weather. The second would operate for short 
periods during severe cold weather and would 
serve as a standby for the first. 

Ventilation and Air Conditioning 

The type of ventilation and air conditioning sys- 
tem suggested for this plant is similar to the one 
suggested for the smaller plant. Three air-circu- 
lating and heating units would be mounted on the 
roof of the plant : A unit circulating 10,000 cubic 
feet of air per minute (54) would be located over 
the main office, a unit circulating 20,000 c.f.m. (55) 
over the empty-case storage room, and a unit cir- 
culating 5,000 c.f.m. (56) over the paper-container 
storage room. 



43 



U. S. GOVERNMENT PRINTING OFFICE : 1963 O